I've had a texture bug with the mounts for some time now. My friends too, playing on the same platform, we bug each other.

During my multiplayer game on Minecraft Switch a peddler appeared but his llamas no longer had any textures. So I asked my friend if he saw the same thing. He assured me to see the same things.

                           Tuesday August 16

I reconnected a day later and this time (I don't have a screenshot) the texture of the mounts had changed again this time it flashes. And my friend told me to see the same thing.

                         Wednesday August 17