You dismount horses when in water more than two blocks deep

You dismount horses when you go into water more than two blocks deep and you cant get them out even with the nameless lead.

I had thought that the horse would swim and swim faster than a person but slower than a boat. I had also thought that the lead would make it swim to shore but it didn't
because it started acting like a sheep does when it eats grass and eventually drowned. This happened to three horses.

I jumped into the water and I was dismounted involuntarily and no matter what I did the horse wouldn't come out of the water not even when the nameless lead was on him.

Steps to Reproduce:
1.Ride a horse into water more than two blocks deep.
2.attempt to put a lead on him.