We have the same issue of being disconnected and losing progress (along with partial rollback i.e. everything is rolled back except last player positon and his horse disappeared/and or disappearing villagers). Although initially, it seemed to be related to villagers killing all villagers with /kill command and removing all the beds didn't fix it for us. No single villager is around and Realms world is still crashing and reverting to last backup. Logs were enabled on owners account but were empty after the crash anyway so no other info. It's happening more often than backup are created and also backups clearly didn't contain all villagers that were there when this backup was created.
Perfectly normal name of my friend [Janusz|https://pl.wikipedia.org/wiki/Janusz] is replaced with ##### in-game when we use it on i.e. name tag. (BTW. Jeb is a curse word in my language 😉 maybe you should censor it?)