For clarification of the pop out video, I mean say you are playing a youtube video, firefox and its forks allow you to "pop-out" that video into a separate borderless always on top window. I use ublock origin for element blocking including advertising and other privacy related features.
I did think window manager extensions as I did play around with the obligatory wobbly windows and the like. But I prefer to have them turned off and have made sure they are all disabled. It was fun though.
A different DE was a consideration but I am a little nervous being new to linux of changing too much and getting myself into a situation where I do not have a GUI. I do have a means to do a system image so would probably wait until I have a recent backup and a system image before changing the DE. Ideally I'd like to fix whatever this issue is but I agree it would be a good diagnostic step.
Thank you for your help.