i have no clue what i have done but now during the night even when its on normal or hard no hostile mobs such as zombies or skeletons spawn at all

both these are likely some structure nearby/in spawn chunks that are eating all the spawns, having cheats enabled and "/incontrol list" should show the mobs that are spawned and theres probably some skeletons/wither skeletons/spiders that are super high

Same experience here. It was fine at first but now there's zero mobs spawning anywhere aside from spawners. Server has only been up for a day.

44 wither skeletons, 54 husks, 68 pigs, 56 mimics, 41 cave spiders... the rest are relatively low counts, there is a pretty large structure in the spawn chunks with a ton of spawners in it. Some massive desert thing.

could probably run a /kill on the wither skeles/husks/cave spiders. mimic count is a little high but those don't respawn and have good loot, aren't in that structure too