Steps to reproduce:
- Tame a horse;
- Use a diamond horse armor, just to check that the color is correct;
- Remove the diamond horse armor and put a leather one in the slot instead;
- Remove the leather horse armor and put back the diamond one
The diamond horse armor is displayed in the default color.
The diamond horse armor color is mixed with the one from the leather horse armor
*Happens to other types of armor as well.
*Reopening the world fixes it.