Which OS do you use?
There has been a problem to copy / paste from eg: Chrome to FireFox in one of the last versions, which also caused problems with drag & drop copy / paste between apps with mobile devices. It all started with a new Chrome version. It seems they changed something in their d&d handling.
I did have to implement some specific code that checks for the UserAgent. Usually we try to avoid such a detection, because it’s very browser specific. But in some cases there is no other way.
I did only test the code against Edge, Chrome, Chromium and FireFox for Windows 11Pro and Ubuntu 22.04 in all combiantions. Copy / pasting stuff from one os-window into an other os-window seems to be both browser and OS specific. I could only test what I have at hand.