YouTube home page mute icon behaves strange and intermittent.

When I select a YouTube home page video mute icon, for sound on a preview, it pops up a mini-player, a notice that I have "saved to watch later," or toggles the mute as expected. Intermittent and unpredictable. I can select one mute icon that toggles the sound, and the preview beside it pops up a watch later. Win10, Firefox 152.0.6 (64-bit) today, but this has been with me about the last two iterations. I ran though eleventy-billion experiments and there was no effect from any toggling of settings, add-ons, file deletions, toggled logouts, forced refreshes, you name it. The single positive is that the keyboard "m" works fine to toggle mute in a video page playback, but not the previews at home. I followed AI advice after I gave up on my own ideas, and after recommending everything under the sun the only conclusion offered was related to failed mouse tracking, which is nuts to me. Everything works fine except this YouTube oddity, including videos or sound output on other sites. I was actually surprised that nothing changed YouTube behaviour after my freaking out on FF details; doesn't mean the trick isn't in there somewhere. In simple terms, I have not read reports of this problem and I have no idea how to proceed.