Some of you may wonder why to nerf horse jump since almost nobody uses horse cause of many different reasons. The reason is that first it's just common logic, i don't think that a horse could jump 10m height no matter the world and 2nd cause it renders some defences useless like if your walls aren't high enough (12 blocks at least) and the rider is persistent he can get inside your place. Spiders are ok in that manner i guess since they are spiders. So that's why i believe that all horses should be nerfed to be able to jump 3-4 blocks at most.