Oh, I cannot edit my post, but I have tried disabling my few add-ons just to be sure one of them wasn't causing it and that didn't help.

harrison.shane wrote: "Ever since switching to Windows 11 I've had an issue with Firefox. Any time I copy something in Firefox, be it image, article text, or even a url from the address bar, I cannot paste it anywhere, and my copy and paste stops working. The only way to fix it is to close Firefox, and then run rdpclip.exe as an administrator. I've confirmed the issue only occurs if I try copying from Firefox, as it doesn't happen in Edge."

I have exactly the same problem. I just want to add one lovely detail. You can copy urls from the address bar - if you copy them into Edge. Very subtle message from Microsoft...