Graphical bugs in KappaPT and NostalgiaVX shaders

[HerryBoss128]

Describe the bug
When using the NostalgiaVX shader pack, surfaces exhibit a strong green tint, making the world unnaturally verdant and washed out. Underground areas show some improvement but still have graphical glitches, such as incorrect lighting and shadowing on blocks. With the KappaPT shader pack, surface rendering appears more normal but with minor bugs present, especially in underground environments which are over-illuminated, similar to the night vision effect. I have verified that these issues do not occur with other shader packs like Photon (in the screenshot). The problems persist even when switching to OptiFine instead of Iris + Sodium, where different graphical bugs are present.

To Reproduce
Steps to reproduce the behavior:
Launch Minecraft Fabric 1.21.8, with mods: iris-fabric-1.9.1+mc1.21.7 and sodium-fabric-0.6.13+mc1.21.6 (the latest versions of both) / with OptiFine HD J6_pre14 Ultra.
Create a new world.
Go to Options > Video Settings > Shaders and select NostalgiaVX or KappaPT.
Observe the graphical glitches.

Expected behavior
The shaders should render surfaces and underground areas with accurate colors, lighting, and shadows based on the pack's intended aesthetic.

Screenshots
Attached are multiple screenshots with the F3 debug screen open for reference, both with NostalgiaVX and KappaPT, as well as Photon as an example.

Environment
OptiFine Version: OptiFine HD J6_pre14 Ultra / Iris (iris-fabric-1.9.1+mc1.21.7)
Minecraft Version: 1.21.8 (Fabric)
Shaderpack Version: NostalgiaVX P2 (2025-09-29.zip); KappaPT F16 (2025-09-29.zip)
Graphics Card and Driver Version: NVIDIA GeForce RTX 5070 (Driver: 581.29)
Operating System: Windows 11 Pro
CPU: AMD Ryzen 5 9600X 6-Core Processor
Amount of System Memory (total and assigned to Java): Total: 32 GB; Assigned to Java: 32 GB

Additional context
I don't know if I'm doing something wrong but I have followed all installation guides for Iris, Sodium, and the shader packs. I reinstalled Minecraft, updated Java to the latest version, and updated the GPU drivers via NVIDIA App. No mods beyond Iris, Sodium, and Fabric API are installed. Testing with OptiFine instead of Iris + Sodium does not resolve the issues and introduces other more significant ones.

[rre36]

These are known issues that seem to happen for a few people with nvidia GPUs, been looking into those for a while but haven't gotten anywhere since I can't reproduce the issues on my nvidia setup.
Also OptiFine is no longer officially supported, even if the versions you have are still compatible.
Assuming you're a Tier 1 subscriber, please check the instructions for the Legacy editions for KappaPT and NostalgiaVX, since those are a bit newer than the ones you're using (more specifically, the last OptiFine compatible versions I released).

[ninetailedtori]

I CR this one, 3080Ti - but it's somewhat uncommon, and typically happens on a bad shader load, and disappears on reload.