1. Two policies, one app. Google Play's Ads policy governs the app itself - "You can also read more about our App Promotion and Store Listing policies here, including how we address deceptive promotion practices" is only one corner of it; the placement rules sit under two headings on the same page, Disruptive Ads and Better Ads Experiences. AdMob layers its own implementation guidance on top and states the consequence plainly: "Not following these guidelines may lead to invalid activity and/or may result in Google disabling ad serving to your app." (§https://support.google.com/googleplay/android-developer/answer/9857753 / §https://support.google.com/admob/answer/6066980)
2. The general test: unexpected, or not dismissible. "Disruptive ads are ads that are displayed to users in unexpected ways, that may result in inadvertent clicks, or impairing or interfering with the usability of device functions." The hard requirement that follows: "Your app cannot force a user to click an ad or submit personal information for advertising purposes before they can fully use an app. Ads may only be displayed inside of the app serving them and must not interfere with other apps, ads, or the operation of the device, including system or device buttons and ports. This includes overlays, companion functionality, and widgetized ad units. If your app displays ads or other ads that interfere with normal use, they must be easily dismissible without penalty." (§https://support.google.com/googleplay/android-developer/answer/9857753)
3. The named violations, in Google's own words. "Ads that take up the entire screen or interfere with normal use and do not provide a clear means to dismiss the ad"; "Ads that force the user to click-through by using a false dismiss button, or by making ads suddenly appear in areas of the app where the user usually taps for another function"; "Ads that display outside of the app serving them"; "Ads that are triggered by the home button or other features explicitly designed for exiting the app". (§https://support.google.com/googleplay/android-developer/answer/9857753)
4. Better Ads Experiences: four banned interstitial patterns. "Developers are required to comply with the following ads guidelines to ensure high quality experiences for users when they are using Google Play apps. Your ads may not be shown in the following unexpected ways for users:" (a) "Full screen interstitial ads of all formats (video, GIF, static, etc.) that show unexpectedly, typically when the user has chosen to do something else, are not allowed." (b) "Ads that appear during game play at the beginning of a level or during the beginning of a content segment are not allowed." (c) "Full screen video interstitial ads that appear before an app's loading screen (splash screen) are not allowed." (d) "Full screen interstitial ads of all formats that are not closeable after 15 seconds are not allowed. Opt-in full screen interstitials or full screen interstitials that do not interrupt users in their actions (for example, after the score screen in a game app) may persist more than 15 seconds." The page notes these are "inspired by the Better Ads Standards - Mobile Apps Experiences guidelines." (§https://support.google.com/googleplay/android-developer/answer/9857753)
5. Rewarded and non-full-screen formats sit outside this rule. "This policy does not apply to rewarded ads which are explicitly opted-in by users (for example, an ad that developers explicitly offer a user to watch in exchange for unlocking a specific game feature or a piece of content). This policy also does not apply to monetization and advertising that does not interfere with normal app use or game play (for example, video content with integrated ads, non-full screen banner ads)." (§https://support.google.com/googleplay/android-developer/answer/9857753)
6. Repetition is a separate violation ("Made for Ads"). "We don't allow apps that display interstitial ads repeatedly to distract users from interacting with an app and performing in-app tasks." The policy's worked example is precisely the pattern over-monetized apps fall into: the user taps Start, an interstitial pops up; after closing it, the user taps Service, and another interstitial appears. (§https://support.google.com/googleplay/android-developer/answer/9857753)
7. Lockscreen. "Unless the exclusive purpose of the app is that of a lockscreen, apps may not introduce ads or features that monetize the locked display of a device." (§https://support.google.com/googleplay/android-developer/answer/9857753)
8. App launch and app exit are the two positions AdMob bans outright. "Do not place interstitial ads on app load and when exiting apps as interstitials should only be placed in between pages of app content. Ads should not be placed in applications that are running in the background of the device or outside of the app environment. It should be clear to the user which application the ad is associated with or implemented on. We recommend placing an app open ad when loading an app or switching back to it." (§https://support.google.com/admob/answer/6201362)
9. Frequency: no more than one interstitial per two user actions, Back button included. "Don't overwhelm users with interstitial ads. Repeated interstitial ads often lead to poor user experiences and accidental clicks." Non-compliant implementations "include but are not limited to: Placing an interstitial ad after every user action, including but not limited to clicks, swipes, etc. You should place no more than one interstitial ad after every two user actions within your app. Please note that this requirement also applies when a user clicks the Back button within the app." and "Placing an interstitial ad immediately after another interstitial ad was shown to and closed by the user." (§https://support.google.com/admob/answer/6201362)
10. It must never get in the way of the app. "Ads should not be placed in a way that prevents viewing the app's core content. Ads should not be placed in a way that interferes with navigating or interacting with the app's core content and functionality." (§https://support.google.com/admob/answer/6201362)
11. Latency is the sneaky failure mode. "Don't surprise users with interstitial ads. Placing interstitial ads so that they suddenly appear when a user is focused on a task at hand (e.g. playing a game, filling out a form, reading content) may lead to accidental clicks and often creates a frustrating user experience. For this reason, interstitial ads should only be implemented at logical breaks in between your app's content (e.g. pages, stages, or levels) to ensure that the user is prepared to engage with the ad." AdMob then names the mechanism: "A common issue is that even though you may intend for the ad to load in between page content, the ad itself appears shortly after a new page of content has loaded due to carrier latency. To prevent this from happening, we recommend you pre-load the interstitial in advance." (§https://support.google.com/admob/answer/6201362)
12. Where to actually put it. "If your app is a game with different levels or stages, consider placing an interstitial ad in between one or more of these stages. A break between levels provides a natural stopping point for the user and allows them to properly evaluate an interstitial ad... Avoid placing an interstitial ad every single time the user does an action." On ordering: "It is recommended that interstitial ads appear before the break page rather than after. Break pages often require a user to tap a Next button (or equivalent). Ads between levels and after a Next button can be surprising. It is strongly recommended that interstitial ads between levels or stages show explicitly before any Continue or Next level buttons. This behavior may reduce accidental ad clicks from users who unintentionally click the ad instead of the Next button." For tap-heavy apps: "it is recommended that a delay is inserted after the end of a level and before the display of an interstitial ad. This delay could take the form of a loading or please wait screen, or a progress-bar/wheel. This offers users a chance to stop tapping the screen and consider carefully what appears next." (§https://support.google.com/admob/answer/6201350)
13. Is an interstitial even the right format here? "Interstitial ads are designed to be placed between content, so they are best placed at natural app transition points." And: "Interstitial ads are best suited for apps with linear user experiences. There should be very clear starting and stopping points in an app. If you have an app that may not meet this criteria (e.g., utility apps like flashlight apps), consider using another AdMob ad format such as a banner ad." (§https://support.google.com/admob/answer/6066980)
14. Close-option delays Google itself expects - and the limit you are held to. "Also, note that some interstitial ads may have up to a 5-second delay before providing a close option. If high-engagement ads are enabled, interstitial video ads may have up to a 12-second delay. Additionally, some interstitial video ads served from third-party bidding sources may have up to a 30-second delay before providing a close option." Those are Google-side realities; the Play-side rule that binds your app is still 15 seconds for any interstitial that interrupts the user, so a 30-second third-party bidding creative is your problem to avoid, not your excuse. (§https://support.google.com/admob/answer/6066980 / §https://support.google.com/googleplay/android-developer/answer/9857753)
15. Housekeeping that prevents accidental clicks. "Make sure to prepare fixed space for ads when loading a new screen in your app. Under certain conditions, such as very low signal strength or phone processing capabilities, ads may not load at the same time as your app content. In this case, ensure that ads do not cover or shift the other content to prevent accidental clicks." And on refresh: "We recommend that you have ads persist for 60 seconds or longer, depending on the functionality of your app... If your app is automatically refreshing ads, make sure ad requests are not made when the screen is off." (§https://support.google.com/admob/answer/2936217)
16. Apps targeting children are held to a tighter bar. There, "Interstitial monetization and advertising displayed immediately upon app launch" is prohibited outright, and so is "Monetization and advertising that interfere with normal app use or game play, including rewarded or opt-in ads, that are not closeable after 5 seconds" - a 5-second closability line, not 15. Such apps must also "Only use Google Play Families Self-Certified Ads SDKs to display ads to those users" and "Ensure ads displayed to those users do not involve interest-based advertising... or remarketing". The page closes with leverage: "Google Play reserves the right to reject, remove or suspend apps for overly aggressive commercial tactics." (§https://support.google.com/googleplay/android-developer/answer/9893335)
17. The sanctioned replacement for an app-load interstitial is an app open ad. AdMob's instruction is to place "an app open ad when loading an app or switching back to it" (§https://support.google.com/admob/answer/6201362), and the format is documented at §https://support.google.com/admob/answer/9620632. It does not buy you an exemption from the dismissal requirement - a full-screen ad that cannot be closed is still a violation wherever it is shown.
18. Do third-party ad networks escape these rules? No. The Play-side text treats ads as part of your app ("The ads and associated offers are part of your app and must follow our Restricted Content policies", §https://support.google.com/googleplay/android-developer/answer/9857753), so placement is enforced against your app no matter which network fills the impression; the AdMob-specific numbers (one interstitial per two user actions, no interstitial on app load) are AdMob program policy and are enforced by disabling ad serving to your app. Accidental-click exposure additionally runs through the invalid-traffic path (§https://support.google.com/admob/answer/3342054).
19. What it costs to get wrong. On the Play side the outcomes escalate from a warning to app removal to developer account termination; on the AdMob side the stated outcome is that ads stop being served to your app. In practice the cheapest fix is almost always the same three moves: delete every interstitial that fires on launch, exit or mid-task; cap frequency at one per two user actions with the Back button counted; and make sure each remaining interstitial has a visible, immediately tappable close control that is not obscured or delayed.