For some reason whenever I open my world up I'll get massive lag spikes and then weird things will happen.  I've had chest minecarts spawn where mobs would spawn.  I've had piglin brutes spawn in the overworld like they were normal mobs.  I'll have mobs teleport to one spot.  They're usually zombies, each holding string, gravel, glow squid ink sac and rotten flesh.  My world exceeded 10 MB so I can't attach it here, but would recommend letting a world run for a bit and then reopen and close it several times and see what happens, especially around a village. Link to world: https://drive.google.com/file/d/19W1ccoxigFKWoCCpJ2TrI2xr6iySJZEp/view?usp=sharing

I have add-ons in the world, mainly having the dragon drop elytra/egg and having custom crafting recipes.  If I remove them the world still lags significantly on opening and still has the strange behavior.  See attached screenshot