Illuminations [Fabric] (previously Lumen)
Illuminations adds fireflies, glowing insects and other light orbs to the world in order to improve the ambience and liveliness of your world both at night and in low light areas.
If you're interested about the mod, you can find more information and images about it on its website (only concerns the 1.12 Forge version; the fabric version only has fireflies, lightning bugs and will o' wisps for now).
If you have any questions, propositions or ideas, please submit them in the Minecraft Curse Forge Project page comment section! Or, you could...