GSR, Buster now has xserver-xorg-core version 2:1.20.4-1+deb10u3 [in-between the versions you quoted] and bullseye now has a newer newer 2:1.20.11-1 version.
Given the date of your bug-report, it looks like you had the old 2018 version of the xorg-xserver package even though the buster package tas been updated twice since then to 2019 and 2020 versions. See Changelog:- https://metadata.ftp-master.debian.org/changelogs//main/x/xorg-server/xorg-server_1.20.4-1+deb10u3_changelog In short, I think this bug report should now be closed unless there is an apparent issue specifically in buster or bullseye now [??] ? --Simon
