Could you please update to 1.21.1 NeoForge?

Have you tried the 1.21 version? It should work.

So yes if I download and drop into mods it works, but if I want to install it via a mod launcher like curse forge or GD Launcher it doesn't come up as a compatible 1.21.1 mod, so it makes it hard for when creating a mod pack. Maybe it just needs to be marked as 1.21.1 compatible?

Yes, done.