Chickens Hatch Now changes hatching for chickens by default. Merely throwing eggs does not spawn chickens anymore. Instead, hatching is more similar to sniffer and turtle egg hatching, albeit with one caveat.
Chickens eggs MUST be placed on top of a hay block to hatch. After this, the eggs will hatch in about 9 minutes!
Info
Modpack devs can change what blocks chicken eggs can hatch on by adding or removing them from
the block tag #chickens_hatch_now:chicken_hatchable. This can be done using either a datapack or KubeJS.