We are experiencing the same issue on the Nintendo Switch. All the horses look black. But when you mount them, you can see their colour. And sometimes they flash between black and their original colour, so it's really painful on the eyes.
Also, if you put armour in one horse, all the horses get the same armour! But they still look black if you look around.
The llamas all look grey. Their colour also glitch between grey and their normal colour. Sometimes the carpet you put on the llama disappears from the animal after you mount, then dismount it.
But the main problem I think is the texture. I'll try to add pictures.
facing the same problem here for over a month now.
My Microsoft Account is properly linked. The Marketplace button is active (not grayed out) but I get the error B-0010 when I try to load it. The issue is not my connection. I went through steps of restarting my router, testing connection, trying to use different connections. Nothing works.
Dressing room shows only two characters. It doesn't let me switch between them since all are marked as "This is your current caracter".
I didn't uninstall the game since I'm not sure if my worlds are backed up. The information on the Minecraft Help page about the "Save Data Cloud" don't match what I see in my Nintendo Switch. Since other players have reported that reinstalling doesn't fix the problem, I'm waiting for a bug fix from Mojang...