Iris shaders reflectionlike glitch

Hi, lately I was trying to play with my friend on our local Fabric server with mods among which we use Iris for shaders. On my side everything works as perfect as it could but my friend is getting weird glitches/artifacts (?) which you can see on his screenshots attached. Could anyone suggest possible cause of those? My gpu is 8 GB Gf RTX 4060 on a laptop His gpu is 6 GB Gf RTX 3060 also on a laptop We play on Minecraft Java Edition version 1.20.1 Shaders we are using: Sildur's Vibrant Shaders Extreme-VL Things we have tried: - Playing without shaders (duh): No glitches/artifacts - Checking his gpu drivers: All up-to-date - Checking if his shaders are for 1.20.1 specifically: They are (Mine are extremely outdated but work just fine) - Using mine extremely outdated Sildur's - Using other 1.20.1 shader packs: Same effect every time - Reinstalling his whole MC installation: No change - Tinkering with settings: Different visual effects and quality but glitches stay the same. NOTE: He didn't try every possible combination so there might be some vital settings he didn't touch - Using said shaders on non-fabric profile with just optifine: No glitches/artifacts Things we haven't tried yet: - Running on his other machine (desktop with different gpu) - Reinstalling his gpu drivers - Giving up Mods we are using: - Cardinal Components API 5.2.2 - Cloth-config 11.1.118 - Traveler's Backpack 9.1.9 - MusketMod for fabric - Daggers 1.3.1 - JEI 15.2.0.27 - Sodium 0.5.3 - Iris 1.6.11 (installed manually) - OptiFabric w/ OptiFine (interchangeably with Sodium w/ Iris) If anyone has any idea what it might be, we would appreciate any help. Thanks!