Minecraft: after update 15.2 world destroyed or distorted?

I have been playing Minecraft for years, I also took all the updates well, but now, since the update to 15.2, my whole world has been destroyed or distorted. I can open the world (s) as normal and play as normal, but whole parts (half houses, water in the middle of the village, large square holes, etc.) are just somewhere else.

Make regular backups of your worlds. Upgrades or downgrades can break things in worlds because in the version they e.g. So do not exist or no longer exist. If you have backups, you can change the version back where it worked. Or you live with the change.