Testflight and AppStore installation fails

I'm working on this Mac Safari extension https://apps.apple.com/app/id6464076425

The installation of the app via Testflight stops without any success (only for me) As well as the installation via AppStore.

This happens only to me. I tried it on another computer, and it installed successfully.

Here are some videos:

This makes the development and release process impossible until I solve this problem.

I tried all the methods I could find online, such as:

  • Deleting the currently installed app
  • Restarting Safari
  • Restarting my Mac

Is there anything else I can do to fix this problem?

Testflight and AppStore installation fails
 
 
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