Firefox will not show WatchESPN in full screen
See attached image. Using Firefox to WatchESPN (https://www.espn.com/watch/) will not go to full screen but leaves black bars at bottom and both sides. This does not happen with Edge or Opera so I use one of those to watch this stream. I get WatchESPN through Spectrum. This happens with both my desktop (Windows 10) and my ASUS laptop (Windows 11). Software versions are all current.
Video from other sources (You Tube, facebook, etc) works fine on all 3 browsers.