Looking at the old module.cmake file, it was never part of the Rendering group. It was probably dragged in by IMPLEMENTATION_REQUIRED_BY_BACKEND (your newest reply seems to confirm that) which is…hairy logic to say the least. It’s tough to say what should be done here because the logic to implement that flag would be extremely difficult to get right.
That’s gone now. Hopefully, the Vulkan backend will be a runtime selection, not a compile-time selection thing.