I'm not sure if this is a bug or an intentional change but the Fairy Slipper used to provide light making a cool way to light up the outdoors without needing torches. I hope this is a bug and will be changed back.

PS: Thanks for all the work updating the mod to 1.20, I really hated playing atm9 with biomes o plenty. So I'm excited to get to play it again with this instead and see the new changes.