I have expirienced a bug where Endermen no longer aggro at endermites. I don't know how many versions this effects but i am in snapshot 20w09a.

Endermite spawned by spawn eggs won't be attacked by endermen (MC-53518). Are you spawning the endermite with an ender pearl?

I did indeed spawn it with a spawn egg!

PS: is this intentional or still a bug?

It's intended, see MC-53518.