The only way that I can reproduce this is by tapping VERY fast. This is always a potential issue when you are using async void for things like button click handling. I would encourage you to use something like RelayCommand from the MVVM Community Toolkit that makes it possible to only allow a single execution of a command. I believe this would help solve your issue.
I'll close this but feel free to reopen if you think I am wrong
Originally posted by @bijington in #2763
It will not fix issue because the problem is that the user can tap many times outside of the popup by tapOutsideOfPopupCommand during popup opening and this command is not RelayCommand and can't be controlled to fix the crash