The bug
Creative mode has an item drop threshold (NetHandlerPlayServer.itemDropThreshold
), but the problem is that this is not considered for all cases.
Currently it is only used when the player throws item out of the creative inventory tabs or when the "Survival Inventory" is open. Other cases like throwing items from the hotbar, or items created when interacting with entities, containers are closed, etc. are not considered.
How to reproduce
Put items in your hotbar
Close your inventory
Try dropping the items from the hotbar as fast as possible
→ ❌ All items are successfully thrown, the treshold was not considered
Attachments
Comments

I'm not quite sure what the expected result is here, and what I should be looking for when I try and reproduce the issue. "the treshold was not considered" is a bit vague to me, could you clarify?
Here is my own test of the issue:
All items are thrown as expected, I'm not sure what's functionally incorrect:
Confirmed in 1.16.1 and 20w29a.