MC 1.17.1
Fabric API 0.40.1
True Secret Rooms 1.1.5

For the purposes of the test I loaded TSR and Fabric API alone, no other mods were used, all resource packs were disabled.

When a slab camo block or a stair camo block is placed on any other slab/stair block respectively, they turn into full blocks instead and copy a texture of a regular stone. When placed on a full block, they still become full blocks as well. Full camo block have the issue of copying stone texture instead of the correct one as well.

Log: [removed] as it's been almost a year, FullSlabs is discontinued and this mod hasn't been updated in a long time too

Example screenshots:

Closing as stale. Will gladly come back to it if the mod receives an update.