When you turned your horse out 24/7 on pasture did you cut the horse’s concentrates?
Whenever I turned a horse out on decent pasture I cut their grain ration (including alfalfa or other legume hay) in HALF. If the horse still was too antsy I cut that in half.
Spring grass can affect horses like it is ROCKET FUEL, my otherwise super calm saint of a horse would all of a sudden “remember” he was half TB, he was born to RUN, and it was off to the races!
Once the “rocket fuel” spring grass matured I monitored the horse’s weight, when I felt the horse’s ribs I wanted a thin layer of fat (around a 1/4" or so), not an inch of fat over the ribs. When the horse started to calm down I would start increasing his concentrates again, slowly over a week or two.
Overfed horses cause their riders many, many problems, lots of falls as they accelerate out from under their riders (BTDT), bucking or through increased shying with lots of body language.
I owned, trained and rode an Anglo-Arab, other part Arabs, several pure Arabs and a Paso Fino, mares, geldings and a stallion. Most of my horses were extremely feed efficient and I had to keep an eye on their weight if I did not want to end up on a rocket ship headed for Mars.