File path for horse armor texture?

Hello, I need help on where to put the horse_armor textures!
I am playing on 1.21.5 and the texture pack is Mizuno's 16 Craft 1.20.4 (I have put Modern Mizuno's on top to be able to play 1.21+).

The second attached image is from the 1.21.2 Patch Notes, I have moved the llama carpet textures there and it worked, no such luck for the horse armors...

Does anyone have an idea? Help is much appreciated!