Every time a website with audio plays in Firefox version 81.0 (64-bit), a pop-up window (similar to the one in the attached screenshot) appears in the upper left corner of the screen. This never happened in previous versions of Firefox. I haven't found a way to disable it, if that's even possible--which I hope it is. The pop-up is not a major inconvenience, just an annoyance, because it disappears after 3-5 seconds or so. Nonetheless, I'd like to be rid of it altogether.