In https://github.com/jellysquid3/sodium-fabric/blob/1.16.x/dev/src/main/java/me/jellysquid/mods/sodium/client/gl/SodiumVertexFormats.java#L97 Sodium converts java floats to unsigned short representation, using (short) (value * 65536.0f);
This is incorrect. Per Khronos docs ( https://www.khronos.org/opengl/wiki/Normalized_Integer#Unsigned ),

For a given integer of bitdepth B, the maximum representable unsigned integer is MAX=2^B-1.

Which in this case is 65535, or 0xFFFF. If we leave the code as-is, 1.0f will encode to 0x10000 instead of 0xFFFF and cause some rare rendering bugs and extremely minor misalignments.

So... multiplying by 65535.0f instead should fix this issue?

Correct.

Good catch. This fixes a number of other z-fighting issues we're suffering from as well.

Fixed with jellysquid3@a7f058b.