Boats from 1.19 cannot be entered in 1.20.  If it was a boat with chest, the chest interface would appear, if it weren't, nothing would change. It is the same effect from shift-clicking the boat. To fix this, you can just replace all the boats on the map, but sometimes this can be bad if there arte too many boats on a realm or old world

In the video, the first boat was replaced before the recording and the second one was the last 1.19 boat from the server.