The libaccounts-glib package does not seem to be getting maintained in Debian, it has had a rc bug (deprecated declarations and -Werror) for 8 months with no maintainer response and has recently picked up a second one (unversioned python removal). It has not had an upload for 3 years.
Both of the rc bugs have been fixed in ubuntu. The ubuntu package has a higher "upstream version" than the Debian one, but this does not seem to actually represent a newer version from upstream. The changes outside the Debian directory between the "upstream version" in Debian and the one in Ubuntu seem to be limited to a small number of changes in the "tests" directory (changing a timeout and removing some gitignore files) and I could not find corresponding changes in the upstream vcs. It seems the Debian and Ubuntu packaging diverged back in 2016. There does seem to be activity upstream with a release 5 months ago, but neither Debian or Ubuntu seem to have packaged it. So I started looking at the reverse dependencies to see if this was a package that was still being used and I found quite a bit. Looking at the first two levels I get: direct: ayatana-indicator-datetime kaccounts-integration kaccounts-providers kio-gdrive ktp-accounts-kcm libaccounts-qt purpose telepathy-accounts-signon second levels: ktp-common-internals (via kaccounts-integration/libaccounts-qt/telepathy-accounts-signon) ktp-auth-handler (via kaccounts-integration/libaccounts-qt) meta-kde-telepathy (via ktp-accounts-kcm) kaccounts-integration (via libaccounts-qt) akonadi (via libaccounts-qt) signon-ui (via libaccounts-qt) choqok (via purpose) falkon (via purpose) gwenview (via purpose) kamaso (via purpose) kde-spectacle (via purpose) kdenlive (via purpose) kdeplasma-addons (via purpose) kdevelop (via purpose) kphotoalbum (via purpose) libkf5pimcommon (via purpose) okular (via purpose) plasma-browser-integration (via purpose) So, it doesn't look like removal is an option. Can someone (perhaps the maintainer of one of the reverse-dependencies take a look at getting this package back into shape?). Bringing across the fixes from the Ubuntu package looks like it would be fairly easy but I have no idea how to test the results.