"VBoxClient --draganddrop" does not terminate at end of session

This concerns virtualbox-guest-x11 6.1.32-dfsg-1build1 in Ubuntu jammy.

When I am logged in to an Xfce session, the view from loginctl(1) is as follows:

 # loginctl list-sessions
 SESSION UID USER SEAT TTY
       4 0 root
     c24 1000 skunk seat0

 2 sessions listed.

 # loginctl session-status c24
 c24 - skunk (1000)
     Since: Fri 2022-05-13 04:53:43 EDT; 41s ago
    Leader: 8502 (lightdm)
      Seat: seat0; vc7
   Display: :0
   Service: lightdm; type x11; class user
   Desktop: xfce
     State: active
      Unit: session-c24.scope
            ├─8502 lightdm --session-child 12 19
            ├─8527 xfce4-session
            ├─8698 /usr/bin/VBoxClient --seamless
            ├─8699 /usr/bin/VBoxClient --seamless
            ├─8705 /usr/bin/VBoxClient --draganddrop
            ├─8706 /usr/bin/VBoxClient --draganddrop
            ├─8806 /usr/bin/ssh-agent -s
            ├─8815 xfwm4
            ├─8824 xfsettingsd
            ├─8827 xfce4-panel
            ├─8831 Thunar --daemon
            ├─8836 xfdesktop
            ├─8839 /usr/lib/x86_64-linux-gnu/xfce4/notifyd/xfce4-notifyd
            ├─8840 update-notifier
            ├─8843 xiccd
            ├─8847 nm-applet
            ├─8887 xfce4-power-manager
            ├─8899 /usr/lib/policykit-1-gnome/polkit-gnome-authentication>
            ├─8927 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper-2.0 /usr>
            ├─8928 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper-2.0 /usr>
            ├─8929 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper-2.0 /usr>
            └─8949 /usr/lib/x86_64-linux-gnu/xfce4/panel/wrapper-2.0 /usr>

After I log out, and wait ten minutes, I see this:

 # loginctl list-sessions
 SESSION UID USER SEAT TTY
       4 0 root
     c24 1000 skunk seat0
     c25 117 lightdm seat0

 3 sessions listed.

 # loginctl session-status c24
 c24 - skunk (1000)
     Since: Fri 2022-05-13 04:53:43 EDT; 13min ago
    Leader: 8502
      Seat: seat0; vc7
   Display: :0
   Service: lightdm; type x11; class user
   Desktop: xfce
     State: closing
      Unit: session-c24.scope
            ├─8705 /usr/bin/VBoxClient --draganddrop
            └─8706 /usr/bin/VBoxClient --draganddrop

The "VBoxClient --draganddrop" program, for some reason, is refusing to exit so that the session can be closed. If I do "kill -INT 8706", then I see

 # loginctl list-sessions
 SESSION UID USER SEAT TTY
       4 0 root
     c25 117 lightdm seat0

 2 sessions listed.

which is what should have happened without intervention.