Version 0.12.1-4 of rust-bat is marked for autoremoval from testing on Sun 22 Nov 2020. It depends (transitively) on rust-onig, rust-onig-sys, affected by #971141, #971147. You should try to prevent the removal by fixing these RC bugs.
vcswatch reports that
this package seems to have a new changelog entry (version
UNRELEASED-FIXME-AUTOGENERATED-DEBCARGO) and new commits
in its VCS. You should consider whether it's time to make