Leashes tied to animals may come off without permission.

Strings tied to animals may come off without permission.

In Ver.1.19.70, the things that tied the animal and the wooden fence with a string may come off without permission.
In my environment, I've checked with frogs and goats.

It seems that not all animals that are tied with a string will always come off the string.
(Several frogs were tied to a string, but some frogs do not come off the string.)