In the end of June one customized form lost all formatting. I could see in the version history that something had happened late at night by it self (63). I published an earlier working version (62 became 64) and everything was fine.
Now the customized form is not working again due to a new version (65) created during night without my involvement. This time it does not help to go back to an earlier version.

The error message is:
"This app stopped working. Try refreshing your browser." Session ID: 9fbdffb9-16f4-4ed5-9662-4aefe07987ca
When I look at the form in PowerApps it looks like this:

What can I do?
Why is this happening?