Hey!
I've noticed the foal image always shows the continent's default background, regardless of what is currently equipped to the horse. This could make for some aesthetically odd combinations, depending on what continent a player is on and what background they have equipped. Some people also dislike the default backgrounds and, precisely for that reason, equip other backgrounds to their horses.
I'd personally love it if the background that was currently equipped to a horse also showed on the foal image, to have consistency.