Yeah, I don't think the underground should look like this.

Every single one of these is a Mythic Metals ore being replaced by waterlogged froglight walls.

This also happens in the nether with its respective Mythic Metals ores, same blocks and overrides.

I love using this mod, but I'm afraid I might have to drop it if this is non-fixable.

This issue is a server-side issue. It does not happen in singleplayer to my testing.

To reproduce:

1. Open a Fabric 1.20.1 server
2. Insert the following mods into the client and server respectively (as well as their dependencies): "More Slabs Stairs & Walls 4.0.0", "Mythic Metals 0.19.9"
3. Launch the server and join from the client
4. If issue is not present, restart the server and then rejoin.
5. Issue should be guaranteed to be there when going in spectator mode and going underground.

Oh, and I forgot this. These used to be calcite stairs and slabs. They're just gone now. Same steps to reproduce, just place them down and restart the server.