This mod simply brings the firefly bush from 1.21.5 to older versions. It works as similarly to the original as possible, emitting firefly particles around itself at night or in a dark environment and playing ambient sounds at night. It can be found in swamp biomes or near any body of water.

This mod comes with a client-side config file. The config allows for tweaking the behaviour and visual aspects of the fireflies.

FAQ

(Disclaimer: All in-game textures/sounds are from 1.21.5 made by Mojang. I did not make them.)