Inconsistency with Nether fungi

As is it shown, there's a problem with emissive properties of nether fungi, they glow in the overworld but they don't in the Nether. This is working with complimentary shaders and the problem remains with or without resourcepacks. Firstly I thought it was because of the Shader, but it works perfectly fine on Optifine, so I was said it is a bug from Iris. Is it there any way to report this issue?