I've also noticed this when farmers interact with the compost. If there is not at least two squares in all directions for them to walk on they'll just fall off the edge.
had this happen as well on a realm game, but myself and the toher player had parrots that kept disappearing. They all seemed to happen after taking a boat a very long distance with parrots. First she lost hers, then I lost both of mine at the same time.
Been having this happen a lot since 1.14. It doesn't seem to happen every time but most of the time when i'm building up a pillar to get rid of the rest of a tree's trunk and start digging back down i'll side to the side and fall off.