I just today figured out what was causing it for me. Apparently having another window (not tab, window) open on anything that involves another video player (100% consistent with Netflix in second window) this issue happens. As soon as I close the second one functionality returned to normal though. Still only started happening with recent update.

Starting having issues around the time this post was made as well. Somewhat intermittent, but only happened after I updated opera gx recently to version 117.0.5408.213. Any solutions that have been found? I've disabled and removed ALL extensions and that didn't change anything.