I am playing in the Minecraft 1.18 beta. I still had all my worlds from before then (1.17) and i was playing them in the beta for a couple of weeks when one day i opened Minecraft and alllll of my worlds were gone. I tried changing the storage settings multiple times from external to internal they did not appear. I also made sure I was signed into my Microsoft account. They still were not there. So i ignored it and made new worlds in the 1.18 beta. About 1 week ago all of those missing worlds reappeared. But then today I went back on Minecraft and all the worlds i made before I got onto the 1.18 beta are gone. And all of the worlds i made while on the 1.18 beta are still here. I'm not too worried because they reappeared before but i spent months on the most recent ones that went missing and the older ones I've had for a year.