Version: 1.21.1 - Neoforge - 21.1.187
Mod Version: Latest

Behavior: Upon closing a dropper inventory, the screen goes black then fades back in.

Other mods: JEI, Sodium, Lithium, Iris (no shaders enabled)

I'm also noticing a flicker on chests and occasionally the pause menu on 1.21, but I have a few mods that tinker with the GUI (like Nemo's Inventory Sorting and Apotheosis).

I wonder if #124 is related.

It's the same when closing anything, lots of mods that tinker with the GUI 1.21.1