All mobs move very slowly especially Slime (with video)

I created a new test world in Minecraft (don't mind a lot of enchanted golden apples and diamond gear). I waited till night time and I was in a deep cave. But then this happened.
All mobs move very slowly while I was in a deep cave. This issue also happened in January 29 2022 as well but with shaders.
Now I turned on night vision pack and it's still the same issue.
Watch this video to see what happened: