When starting my forge 1.16.5 server a list of errors popped up, in the pastbin below I included all the Quark errors. The main error was GlobalEntityTypeAttibutes error but there was also a few Trying to add entity duplicated error. There was a lot of passive mobs spawning (I think because of the Trying to add entity duplicated error) and ghost blocks would start at a random time and not stop in till we restarted the server.

Pastbin: https://pastebin.com/RRG9AZ7H

Even if you don't have solution if you could tell what the errors mean that would be great too.

There were other people that had this problem to.

#3369
#2975
#3160

These issues aren't related, and are just warnings, you don't have to worry about them.