I have a free and paid version of the same android app. Some users (always using Samsung tablets) reported that the camera preview was stretched with one of the apps, and OK with the other.
I managed to find a Samsung Tab A6 to reproduce the problem. I first realized that the difference was that one of the app was using a different display density, width and height. Then, using "adb logcat", I saw logs about requests to https://service.game-mode.net/gamemode/v3/packages/ with my app pakage name as a parameter. Other logs for same PID indicated: "SELinux : SELinux: seapp_context_lookup: seinfo=platform, level=s0:c512,c768, pkgname=com.enhance.gameservice". From what I saw on the net, "com.enhance.gameservice" is a Samsung Game Optimization service.
So far, I have found 3 ways to fix the problem, but none of them can be a solution for my users. The problem disappears if:
My problem looks related to Galaxy Note 5: Density Reduced Automatically. Unfortunately, Game Tuner app which is mentioned in the accepted answer, is not available on all Samsung tablets (it is not available on my Galaxy Tab A6).
Is there a way to get rid of the interactions with the Samsung Game Optimization service? Note that my app is not a game.
I answer my own question.
I used the contact email from Game Tuner (https://play.google.com/store/apps/details?id=com.samsung.android.gametuner.thin) hoping they could do something about my issue. A few hours later, I got an answer indicating that my app was wrongly categorized as a game and that they changed it but that I needed to wait 1-3 days before all devices are updated. One day later, I could check that I got category_code":"non-game" in the response from https://service.game-mode.net/gamemode/v3/packages, and that my issue was fixed.