The new link is here: https://packages.debian.org/buster/libs/libxosd2 It's this one http://deb.debian.org/debian/pool/main/x/xosd/xosd_2.2.14-2.1.debian.tar.xz Updating it and updating the checksum should fix it.
Flagged Out-of-Date Comment: xosd-ex
Quatro flagged xosd-ex out-of-date on 2021-01-30 (UTC) for the following reason: