My nether turned into another version of the overworld that is always dark and it has just about everything i did in the overworld with a few exceptions, probably due to when the game last saved.

What I expected to happen was...:
to end up in the nether.

What actually happened was...:
something way scarier, as wither skeletons where spawning everywhere you, turn plus all of the overworld hostile mobs, with what seemed to be no restrictions, except the areas i had previously lit

Steps to Reproduce:
1. I kept on trying to replicate the issue, but to no avail.
2. All i do know is that i was on hard, I was trying to kill a straggler zombie pigman that escaped the nether, but i ended up hitting him in the portal so i decided to follow. The nether didn't seem to load in properly then i herd the pigman die and found myself in this hybrid dimension.
3. ...