Videos recorded by Ring Stick Up Cam no longer playable in Firefox. What is going on?

I have a Ring Stick-up Cam. I've had it for 7 1/2 months, and it has worked fine without any problems.Yesterday, the past month's worth of recorded videos suddenly became unplayable in Firefox. "Video was recorded using a modern HEVC video format called that is not supported on this browser."After talking with customer support for a little bit, it was determined that it's a Firefox issue. So I went to the Firefox community for answers. That conversation is still in progress.The response so far is that windows media foundation usually decodes encoded stuff for playback, but if that was acting up I'd probably notice playback issues elsewhere, and a link to a thread where switching to legacy mode was the only solution anybody came up with so far.I have found the legacy mode thing, and newer recordings seem to be working. That doesn't really explain though, what the problem is, and how to fix it. It seems like the explanation is that there is basically a compatibility issue between the way some Ring products record their videos, and Firefox's playback options. The problem I have with that is everything was fine for 7 months. The issue only showed up 24 hours ago.So I'm trying to figure out what changed, and what I might try to do to fix it.Ring says it's a Firefox issue, Firefox says it's a Ring issue, and nobody seems to be able to give me a solution. Is there anybody else who has encountered this and has come up with a fix for it.