Mobs are spawning superfast and in well lit spaces

So I know that this was already reported but it said it was fixed but it wasn't so I'm still reporting it. 

So I was playing with my dad in the nether and there was a whole bunch of blases so we killed them but then like eight ghasts spawned in a minute so I went home and then a whole bunch of mobs spawned, even ones that aren't supposed to be in that biome like slimes, and our base is really well lit up.

Ps, I couldn't get a screenshot.