As part of an ongoing thread on the Evolution list:
https://mail.gnome.org/archives/evolution-list/2020-February/msg00041.html
it turns out that logging into KDE creates a new session (in the sense
of loginctl(1)) but logging out doesn't terminate it. Thus every time
you log out and in again the number of sessions increases. You can
verify this by running 'loginctl --list-sessions'.
Is this a bug?
poc