How not to loose over 90% Android app users with the new Sdk version (Android 14)?

1. I wanted to upload my app bundle to App Store, but the Android version was not enough (has to be at least 14);
2. I updated my app updating SDK from 33 to 34 and kept minSdkVersion 21 - resulting an error: minimum Sdk version has to be at least 33;
3. Updated minimum Sdk version to 33 and was able to upload my app bundle to App Store.
4. Since that high Sdk version referres to Android 14, App Store shows me a warning that I will loose over 90% of my app users.

How not to loose that many users and let them still use new, fixed and updated versions of my app?

You're mistaken in what SDK version you changed. There's minSDKVersion and targetSDKVersion. The play store requires you to have the targetSDKVersion to be at least 14, but the minimum can be as low as you want. So change the minSDKVerion back and adjust the targetSDKVersion instead.

The difference between the two- the minSDKVersion is the lowest version of Android your app will run on. The targetSDKVersion is the version you're targetting. Changing that changes how some APIs behave, they will keep legacy behavior if your targetSDKVersion is older.