I dug a little deeper and found out there's a transition [1] in the works to a new 2.0 version of the library with a different soname which supports version 2 of the bittorrent protocol. I guess the transition will resolve before the package is autoremoved? And maybe I'll try my hand at backporting this new version to bullseye once it reaches testing.
[1] https://bugs.debian.org/1001830
