I have Arch linux with KDE Plasma 5.23 and newest available 1password installed. I have the same problem on Wayland and Xorg.
The very top left corner of my screen has an invisible 1password menu of sorts. When a window is expanded full screen, I cannot click on anything that is right in the top left corner. If I leave my mouse there, I get a tooltip that says 1password. If I right click, I get the same 1password menu that I would get when right-clicking on the system tray icon. I can quick 1password, and then the area is now clickable again.
I have my close button on the left side, so I can't click to close a full size window.
This is very strange. Here are three screenshots to explain:
1Password Version: 8.3.1
Extension Version: Not Provided
OS Version: Arch Linux