After logging into my Minecraft Realms server, I've encountered an issue where previous activity (ie. building, digging, etc.) has been reset to a world state from a few hours prior.
I had been removing large portions of dirt, chopping down a section of a forest, and adding large sections of dirt to a nearby area, and then I had logged off. I do not know if anyone else was on the server in the period following my log off, but as soon I relogged on to the server all of that progress had been reverted to a previous world state.
This appears to be a duplicate of REALMS-4224, which hasn't yet been resolved. If you have any additional information to provide regarding this issue, feel free to comment on the parent ticket. If you feel that this issue is affecting you, feel free to vote for the duplicated ticket, to give Mojang a basic idea of how many people are impacted by the problem. Just to further inform you, this will not determine how quickly the bug gets handled or fixed.