Certain blocks (non-full-solids + custom) appear displaced in first-person with Iris shaders when set in item-form or when dropped

[EtherealLlama]

Versions:
MC Version 1.21.11
Locomotion 0.1.11 Playtesting Release
Fabric Loader 0.18.4
Fabric API 0.41.3
Iris 1.10.5

Issue:
Under certain conditions, some transparent blocks like slime, glass, or glass panes don't appear in their actual location. They float on-screen, moving with the player but seemingly fixed in a different location in the world.
The items appear as expected when shaders are disabled, when viewed in third-person mode, or when first-person animations in Locomotion's mod menu are disabled.
Tested and seen with different shaders such as Complementary, Bliss, BSL, and Photon.

Conditions to reproduce:

• Be in first-person mode
• Have shaders enabled
• Drop the item from inventory OR place the item in a shelf or item frame.

Minecraftsingleplayer.1.mp4

I've also seen this in a multiplayer server (ImagineFun). Since as they use a lot of custom blocks, I can't say exactly what's going on - just that it seems to follow the same problem conditions as above.

Minecraftmultiplayer.2.mp4

[AydinRW]

Could you please tell me how to add a video in an issue? I also want to add a video in my issue. Thank you.

[EtherealLlama]

Could you please tell me how to add a video in an issue? I also want to add a video in my issue. Thank you.

@AydinRW You can upload MP4 and MOV files as long as they're under a certain filesize (for most accounts it'll be 10MB or under). Use a video compression tool or something like Handbrake to get there!

[AydinRW]

Could you please tell me how to add a video in an issue? I also want to add a video in my issue. Thank you.

@AydinRW You can upload MP4 and MOV files as long as they're under a certain filesize (for most accounts it'll be 10MB or under). Use a video compression tool or something like Handbrake to get there!

Thank you, that worked! It turns out the issue was that the video I uploaded earlier was larger than 10 MB, which caused the upload to fail. Also, the HandBrake you recommended is really handy—thanks for that as well!