Mods:
cullleaves-2.2.0.jar
fabric-api-0.36.0+1.17.jar
indium-1.0.0.jar
sodium-fabric-mc1.17.1-0.3.0+build.5.jar

Vanilla

Sodium * graphics settings ended up being a bit different but regardless of options this behaviour is present

this is more obvious when you are on top of a tree that passes into a new chunk on the XYZ as the backface will not show for chunks outside of the one you are in.

this does not happen with other model-based resource packs, your own https://www.curseforge.com/minecraft/texture-packs/motschens-better-leaves seems to renders fine with sodium as expected.

turns out this affects all models in sodium.

solved. sodium 0.3 was missing the ability to disable BlockFaceCulling.