I installed Embbedium 0.2.18 MC 1.20.1, along with Little Tiles and Creative Core (latest version & no other mods installed). These pictures below show how Little Tiles blocks are shaded with/without Embeddium:
With Embeddium installed:

Without Embeddium installed:

I don't know whether this is Little Tiles's issue or Embeddium's issue. I've told Little Tiles's author to contact you if necessary.

This issue needs to be fixed on LittleTiles' end as it injects custom patches into Embeddium. I believe it is solved in the latest update.