Blocks and NPC entities are gone. And then they multiplied.

My farm animals, dogs, villagers, golem, and the road are GONE.
WTH IS THIS?

PS: the other mobs are not gone, the nether is fine.

Please help.

20/01/21 UPDATE: The paths, villagers, golem, animals are back!
BTW: THEY MULTIPLIED!

Now I have twice the numbers as before. The only exception is my dog. This is just weird.