Hi, I am also having problems with weak password warnings but found a funny workaround for this issue:
The password of a login is marked as "terrible" (though it was generated by 1Password). I now edit the item, let 1Password generate a new password (copied the old one to the clipboard before) and save it. After that I edit the item again and replace the new password with the old one by pasting it from clipboard. After saving the item again the password is now marked as "fantastic". The "weak" password has been generated with 1Password 7.x.
1Password for Windows 8.7.3
Windows 10 Pro (21H2) 64-bit