That used to happen a lot to me, but thankfully it hasn't happened recently, although I still have the reflex to refresh the page when my opponent isn't moving for some time or when it says that my opponent disconnected as, in the past, I would often be the one who losses in such situations as described in several earlier comments. I don't know exactly, but I think this hasn't happened to me in a year or so.
My opponent runs out of time ... and wins on time!
At least once, maybe twice, the "Time" for myself and my opponent switched, so they instead of being out of time as they were under a minute or two , got my time, over five minutes left, and I got their time and then I lost on time out, or drew on time out due to them not having enough material to win.
I played 34...Rd1 with mate coming next move. My opponent let the timer run out then nothing happened. Few minutes later, I clicked on his timer which was 0:00 and game said I lost on time? WTH!! My setting says claim auto victory on timer run outs already.

I played 34...Rd1 with mate coming next move. My opponent let the timer run out then nothing happened. Few minutes later, I clicked on his timer which was 0:00 and game said I lost on time? WTH!! My setting says claim auto victory on timer run outs already.
You last move didn't make it to the server. You must have been disconnected.
https://www.chess.com/game/live/95736678275
That said, the live server was having issues around the time of the game so you might open a ticket and support may be able to refund rating from the game.
At least three times since August 2022, THIS YEAR, I was ahead in position, pieces and time, or part of the above, with plenty of time on my clock,
and the opponent running down to ZERO on his clock, as THEY WIN ON TIME ? Sometimes the time on both clocks, mine and opponents, reverses place a couple minutes before running out.
This is either on purpose, or a hack .... anyone find out ?
That sounds exactly like your client being disconnected from the live server.
It's not a hack. The clients never directly connect and your opponents can't see your connection details.