Thank you for checking is out! Unfortunately the support for (baked) lightmaps is still missing for the compatibility renderer. High hopes for Godot 4.3 to reimplement it.
Can check how it would look on the dev build just out of curiosity, but figured it's better to release on a stable build of the engine.
Another option would be to bake it into textures, yet that would've eaten a lot of time that we just didn't have.