Is it impossible to update the apps in Google Play Console with Google's latest changes?

General Discussion
7
  1. Which builder (AI2, Kodular, Niotron, ...) was the app created with?
  2. When was the app created and published in the Play Store.
  3. In which format was the last app version built / uploaded (APK or AAB)?
    See also here: Signatures for App Bundles - #5 by Anke
  4. Which keystore was used for the original (last) app version. Was the app signed within the build server (AI2, Niotron, ...?) or subsequently outside the build server (like I have been doing for years)?
  5. Was the original keystore backed up (saved)?