Important Note
From 1 Aug 2021 every new app must target Android 11: targetSdkVersion = 30 !
See also here.
AI2 has not yet released a corresponding update (up to now). Therefore it is currently not possible to publish a new app in the Play Store unless you manually set targetSdkVersion to 30 in the decompiled APK. EDIT: You must also use AAB for new apps! (So my guide is obsolete.)