My Nether is broken, chunks are completely missing in random spots, and it deleted my portal and everything around it that I built.

I loaded a save file of my world and went to a fortress that I use, and nothing seemed wrong other than random chunks completely missing from the Nether, and when I got back to where my portal is, it wasn't there. I think the 1.16.210 update reset a small part of my nether and made whole chunks disappear. This only happened in the Nether for me, and everything else seems fine.