I contacted Support about this problem, but I haven't received a response yet, so I decided to try something on my own. I uploaded a new version of the app to the App Store and checked if the old version could be replaced with the new one.
Good news! It worked! On devices where the old version was installed, I was able to update the app when the update became available on the App Store. The new version replaced the old one smoothly, which TestFlight couldn't do after the app transfer.
After installing the app from the App Store (after the app transfer), I could install the TestFlight version or the new version without any issues.
To help others understand and solve similar problems, I created a graph that shows the process. After transferring the app, the beginning of your AppID automatically changes to match the new team. Because of this, you can't install the new TestFlight version on the old TestFlight version because AppIDs do not match. However, once an app is uploaded to the App Store, it has been signed by Apple - even if it has the old AppID, you can still replace it with the TestFlight version or a new version using the new AppID in Xcode.
I hope this graph helps others facing similar problems:
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Yes it is. It also crash when you try to draw a very long stroke with pencil tool.