Similar issue here that got a lot worse with 1.21.5, but it was happening previously too. Player count doesn’t seem to affect the crashes we are having and we will often lose up to an hour or more of progress.
Same problem but it got much worse with 1.21.5
It crashes super frequently and rolls back a lot of progress.
Same for java but my issue was marked resolved for being a duplicate. Yours probably will be too but I have no clue which bug report would be the ‘main’ one to keep track of 😕