Basically, taking boats anywhere and then leaving them will result in them disappearing. Here's an example:

https://twitter.com/rainbowdovess/status/1465876128195756043

Though I forgot to take a video to prove such, it seems like the boat is teleporting rapidly back and forth, or at least some part of it is - I saw a parrot I had put in the boat flickering in the distance after it happened when I left that boat.

This was minorly prevalent in the update prior, but I was using boats on ice when that happened, so that made a little more sense.

Thank you and loving the rest of the update!