Mobs in nether fortresses spawns very rarely

Mobs in fortresses spawn very rarely now, don't know if this may occur due to reverting spawn mechanics, because I don't know if they've been readded yet, but blazes and wither skeletons spawns much MUCH less frequent than in 1.15. May not affect soulsand valley and warped forest

 

Seed:-2307589128541860495

Coords: /execute in minecraft:the_nether run tp @s -700.93 81.62 552.35 190.50 37.65

Superflat void preset