On Kubuntu Desktop, KDE Plasma session fails to re-launch ssh-agent upon logging out and logging back in again. The SSH Agent environment variables for the previous session persist. Package: plasma-desktop Version: 4:5.12.6-0ubuntu0.1
This is probably not a KDE bug, but instead an Xsession script bug. Ah, yeah, the script in question is provided by x11-common. I'll see if I can report it to them. Here's the workaround anyway, if anyone finds this incorrect bug report before I launch one against x11-common on Ubuntu.
Created attachment 114669 [details] Patched Xsession.d script that fixes the issue
Thanks for finding this! Please do report it to the xsession and Ubuntu folks.