I have a realm, on IOS, and it roll back when we have a certain number of players, it roll back for everyone. I already contact Mojang for help and I receive some help from BlessedMoonLord and Cobble, they sadly don’t find nothing else can cause this issue. Actually Cobble say me "You are more than welcome to try submitting a bug report again. Once you do, please mention that we've already checked your realms and were unable to locate anything on a surface level.” So I am doing it. Cobble say me too to say this "Specifically this issue seems to occur when a certain number of players join your realm, then everyone disconnects from the realm and progress is rolled back.” Thanks!