Hand Position bugs when going to F5 mode while riding a horse

Tame a Horse, Put a saddle on it and Armor too, Ride It and Press F5 , Jump, Walk a while and then Exit F5 mode, Your hand position will be bugged, And it will never fix, no matter if you exit the world, come back , Stop riding the horse, Your hand position will still be bugged, Which can be very annoying