Android studio lets you analyze apks and you can check more or less why the size is so big. Last time I checked it was a mix of assets (images mainly) and rare

Android studio lets you analyze apks and you can check more or less why the size is so big. Last time I checked it was a mix of assets (images mainly) and rarely used functions. In the case of app compat almost all is due to backward compatibility. That library allows you to use features intended for newer APIs, but making it compatible with older versions. This has advantages (mainly the themes) but it also means that the apps contains a lot of assets and code that will never run. The app bundle reduced this problem, but it's still present.