When theres lots of mobs around you the game starts making the mobs move in slow motion and same if you drop items when this is happening.  For example I have a village with 20 villagers and I started a raid and the game started doing that. The frame rate was pretty much fine but all of the mobs started moving in slow motion and if I dropped items out of my inventory they would move in slow motion as well. The same thing happens when you have lots of dropped entities on the floor. You'll run through them and it's like your character doesn't even exist and doesn't pick any of them up. So you have to run through them several times just to get them to pick up. And block lag is back and worse then ever and I'm playing by myself not on a server.