I don't mean to make this sound like an advertisement, but I have already backported the armor trims from 1.20.

I would just like to let you know so that you can stop pulling your hair out over it.
Here is the curseforge link and source:
https://www.curseforge.com/minecraft/mc-mods/armor-trims
https://github.com/Hipposgrumm/armor-trims

Hi! I'm currently working on the update of my mod with the armor trims. ^^

It might be notable to know that the mod isn’t 100% stable and that I am working on updates to make it better.