I have a coming 3-year-old Morgan gelding (3 on 2/28) who has never been level in the entire time I’ve had him - brought him home at 7.5 months old. Just when it looks like his front end might catch up, his butt goes up again.
My first yearling was never more than 1/2" different while he was growing up (he’s 20 now). I figured they were all like that. My 2nd yearling was at one point 4" butt high, mostly 2", and didn’t level out until his last growth spurt at 7.
Pic is the 2nd yearling (Aries). He’s not standing in a hole. LOL
(I’ve used this picture before, but he is the worst horse to take pictures of, and this is the only good one I have. LOL)