yo so in bmc4 there is only aether dragon but i know there should be more than just the aether dragon there should be more variants i have updated the mod and no fix can you help?

There isnt anything wrong here. The mod registers all dragon eggs under the same item ID. The different dragon egg variants are decided by NBT data thats attached to the dragon egg. You will still be able to find the other dragon eggs by exploring and killing the ender dragon.

There's an addon mod that fixes this:
https://www.curseforge.com/minecraft/mc-mods/dragon-mounts-patches