What is the issue?
Chunks Fade In, doesn't fade in chunks with nvidium installed

Conditions to reproduce
Load up a world and press F3 + A

Does this issue appear only with Sodium, Iris and Chunks Fade In?
No, only when nvidium is installed
https://modrinth.com/mod/nvidium
https://github.com/MCRcortex/nvidium
MCRcortex/nvidium#56

Full Minecraft logs

WITHOUT nvidium

WITH nvidium

Well... Nvidium is Incompatible with many graphics mods, but I'm also wondering if this can be fixed

I think this will require a rewrite of a pretty big chunk of Chunks Fade In code. But currently I don't have access to a Nvidia GPU, so there is no way for me to fix this issue and test my changes

damn that sucks that you don't have access to a Nvidia GPU. I guess I should close my issue on Nvidium as not as planned as this seems to be an issue with Chunks fade in, right?

I should say
do you think Nvidium could add compatibility on their side or no

I have no idea how mesh shaders work and I'm almost certain that Nvidium developers also can not fix this issue. Probably someone with a Nvidia GPU, experience in modding and mesh shaders can create a pull request that will fix this, but no hopes also

It is possible its just... not fun to do and would have (probably small) performance impact

I was going to report this exact same thing, but I wasn't aware yet that it was nvidium causing the issue, but what I came across was that the mod does work if Iris is installed with a shaders enabled even if nvidium is installed too, im not sure if Iris effectively disables nvidium when a shaderpack is enabled. and if its not perhaps looking through Iris's code could bring some light to this?

As I know, yes, Nvidium is disabled when Iris shader turns on.
This is done because Nvidium uses completely different shader pipeline (exclusive to Nvidia GPUs) than Minecraft with Iris/Optifine/etc. Because of that, shaders made for "normal" Minecraft will not work with Nvidium and vice versa. It is actually possible to make shaders specifically for Nvidium, but I don't know if any mod implements this yet.