Hello! It seems like we might be facing similar issues where our TestFlight and Appstore applications cannot be downloaded, using the same OS version of Mac as well. Have made a post earlier regarding this issue as well, but so far no one has replied: https://developer.apple.com/forums/thread/797150 Gonna leave a boost so that someone from Apple can take a look at this issue soon! :(

Forgot to mention, but I have also raised the issue through email with case ID: 102669467940. But this post has additional information that was not in the email.