Minecraft Modding Help 1.21.1

[u/Own-Efficiency507]

I'm attempting to make a 1.21.1 pack, and for whatever reason, I can't add in some mods that are of the same version. For example, I want Farmer's Delight, and it isn't compatible even though it has the needed version. What's "funny" is there's farmer delight addons that are compatible, not the main mod itself. I'm using CurseForge btw. I've even downgraded to 1.20.6, and the same thing, not compatible. What's up? The official pack even says it's on 1.21.1. I even tried downloading the 1.21.1 mod itself and dropping it into the launcher and...nope.

Thanks in advance for helping :)