Suggestion
Mushrooms (and large mushrooms) should be able to grow on mushroom fertile soil at any light level, like mycelium

Current Behavior [Optional]
Mushrooms don't sprout in light level > 12.

Justification
Requiring a darkroom to do what is already tricky automation is unnecessary, and makes it harder to see/admire your own setups.

This feature was not able to be added without ASM/transformers in MC1.16.1, but will be possible in MC1.16.2 due to the addition of a new tag.