When I am traversing large quantities of water, I usually put my Donkey into his own boat and then have a lead on his boat, while I myself travel within a "boat with a chest". However, after update 1.20 the ability to put a grown-up horse or donkey in a boat has been removed.? I am unsure if this is intentional or not because I can't find anything in the new patch notes clarifying this change. I have tested in creative mode if other mobs such as sheep and cows have this issue, but they do not. Only child donkeys and horses can enter boats right now.