I have a Realms world, where my friend and I play.  He is about 1000 blocks away from me in both directions.  Both his map and my map have remained relatively untouched by the recent updates, however all the maps that I have explored around the area are rewriting themselves incorrectly from what they were before, and they have these long random chunks appearing out of nowhere.  The heights of these random chunks are very tall just out of water mostly.

I even found where the end portal should be, however because of rendering issues with the height, the end portal area is all distorted and I haven't been able to find the portal itself.

I also found a treasure map that was pointing me to a piece of land.  When I got to it, it was only water.  The treasure map was also wrong.

This happened when 1.17 came out and I gave up on the map and started over again.  I have spent countless hours rebuilding everything, and now this happens.

Is there any way to fix the worlds to stop this from happening?  If so, how do I get it back to a known good state?  I am using the experimental settings, but have never had problems like this before.  With major updates happening to the game, what's the point in playing it if every update completely destroys the world?   I don't want to continue playing on my world if I can't fix it.  There is no option to go back to a previous version of Minecraft like you can in Java.  

Can someone please help!