This issue is already happening since a while back with older versions of Firefox and 1Password X.
The issue isn't happening while Firefox is still starting up but as soon as Firefox is longer running pressing the unlock key combo or unlocking it from the menu will crash Firefox as soon as I entered my password and pressed the button to unlock 1Password X. Normal 1Password integration works without any problem.
When reinstalling 1Password X it's working for some time but then gets back to crashing (except when unlocked while Firefox is still starting up).
1Password Version: 7.6.785
Extension Version: 1.22.3
OS Version: Windows 10 20H2 (Build 19042.662)
Sync Type: Not Provided
Referrer: forum-search:firefox crashing when unlocking 1password x