Tree leaves are generated, falling water, very horrible mountains are generated

As you can see in the image things like these are happening in a survival that has more than a year, this is repeated many times around the world, luckily I have made backups. I will not really play until it is fixed as I am generating this everywhere and it is very annoying. In addition to that mountains are generated in ALREADY LOADED chunks that are really horrible at sight. That perimeter was from a slime farm that less than a week ago, I removed it and the perimeter was thus empty, a perimeter that has been done for months and since previous versions. I need an answer, thanks for reading.
Sincerely:
Federico Madriles Sanchez
I am Mexican, and I have used a translator, yes.