When riding a horse in bedrock and you are genorating new terrain, these invisible barriers appear frequently and only affects  certain areas. These Barriers are unable to be passed through by the player or it’s mounts. However   Apon dismounting or the mount (any mob or item) touches the barrier it will begin to vibrate visualy, but they are still moving (but they are invisible) and can attack the player. Sometimes the damage appear immediately and sometimes it take leaving and rentering the world to get it to show up. If you get in water near the barrier you will not be able to get out again. When in the water near the barrier (3-4 blocks) the water loses its physics and you walk instead of swimming, but your air still goes down.