Hi, So, snapd sets $PATH and $XDG_DATA_DIRS in /etc/profile.d/apps-bin-path.sh, but /etc/profile and /etc/profile.d aren't used in the graphical logins in Debian. [1]
Older versions of snapd also had set $XDG_DATA_DIRS in /etc/X11/Xsession.d/65snappy, which was used in the X sessions. But that was dropped upstream in [2], which happened some time after Stretch was released, but before Buster was released. I guess this is the cause of the problem... [1] https://wiki.debian.org/EnvironmentVariables [2] https://github.com/snapcore/snapd/pull/3398
