Problem with connected textures with the Chipped mod when using Advanced Colored Lighting with Complementary Unbound and Euphoria.
Works fine with just regular Complementary Unbound using ACL.
Only setting changed is ACL.

Problem:

Working fine (regular Complementary shader)

Using ComplementaryUnbound_r5.5.1 + EuphoriaPatches_1.6.2 and Iris 1.8.1 on MC 1.21.1
Problem was also present for ComplementaryUnbound_r5.4 + EP_1.5.2

Only possible fix for now is going to other > acl features > and disabling connected glass. In the future we might be able to fix it. But it would be a bit annoying

Thanks! That'll do for a solution for me.

What's the exact block called?

This block is called Fancy Black Stained Glass, but the problem was present with all of the few glass types from the mod that I tested with.