I did see that post, my behavior is different, from what I can see, that poster appears to be able to start the service, and it crashes when they add a file, mine does not start at all. Posts between when I read that and posted this seem to indicate there is a SAB issue, so you are likely correct that this is related. I will monitor that thread and the SAB issue on github.
Journal file /var/log/journal/5d7bab61e51c4e2cb276d5cb1f6cc9a6/user-1001.journal is truncated, ignoring file.
Aug 04 20:39:49 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:39:50 Wildstyle SABnzbd\[470507\]: double free or corruption (out)
Aug 04 20:39:50 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:39:50 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:39:51 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 1.
Aug 04 20:39:51 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:39:52 Wildstyle SABnzbd\[470589\]: double free or corruption (out)
Aug 04 20:39:52 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:39:52 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:39:52 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 2.
Aug 04 20:39:52 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:39:53 Wildstyle SABnzbd\[470713\]: double free or corruption (out)
Aug 04 20:39:53 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:39:53 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:39:53 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 3.
Aug 04 20:39:53 Wildstyle systemd\[1\]: sabnzbd.service: Start request repeated too quickly.
Aug 04 20:39:53 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:39:53 Wildstyle systemd\[1\]: Failed to start sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:45:21 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:47:04 Wildstyle SABnzbd\[475830\]: double free or corruption (out)
Aug 04 20:47:04 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:47:04 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:47:04 Wildstyle systemd\[1\]: sabnzbd.service: Consumed 2.591s CPU time.
Aug 04 20:47:04 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 1.
Aug 04 20:47:04 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:47:05 Wildstyle SABnzbd\[481644\]: double free or corruption (out)
Aug 04 20:47:05 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:47:05 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:47:05 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 2.
Aug 04 20:47:05 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:47:06 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=11/SEGV
Aug 04 20:47:06 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:47:06 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 3.
Aug 04 20:47:06 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 04 20:47:07 Wildstyle SABnzbd\[481830\]: double free or corruption (out)
Aug 04 20:47:07 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 04 20:47:07 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:47:07 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 4.
Aug 04 20:47:07 Wildstyle systemd\[1\]: sabnzbd.service: Start request repeated too quickly.
Aug 04 20:47:07 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 04 20:47:07 Wildstyle systemd\[1\]: Failed to start sabnzbd.service - SABnzbd (DietPi).
Aug 05 07:02:35 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 05 07:02:36 Wildstyle SABnzbd\[940841\]: double free or corruption (out)
Aug 05 07:02:36 Wildstyle SABnzbd\[940841\]: free(): invalid pointer
Aug 05 07:02:36 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 05 07:02:36 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 05 07:02:36 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 1.
Aug 05 07:02:36 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 05 07:02:37 Wildstyle SABnzbd\[940966\]: double free or corruption (out)
Aug 05 07:02:37 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=6/ABRT
Aug 05 07:02:37 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 05 07:02:37 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 2.
Aug 05 07:02:37 Wildstyle systemd\[1\]: Started sabnzbd.service - SABnzbd (DietPi).
Aug 05 07:02:38 Wildstyle systemd\[1\]: sabnzbd.service: Main process exited, code=killed, status=11/SEGV
Aug 05 07:02:38 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 05 07:02:39 Wildstyle systemd\[1\]: sabnzbd.service: Scheduled restart job, restart counter is at 3.
Aug 05 07:02:39 Wildstyle systemd\[1\]: sabnzbd.service: Start request repeated too quickly.
Aug 05 07:02:39 Wildstyle systemd\[1\]: sabnzbd.service: Failed with result ‘signal’.
Aug 05 07:02:39 Wildstyle systemd\[1\]: Failed to start sabnzbd.service - SABnzbd (DietPi).
It looks like they are in fact the same issue, and the fix provided there has got me back up on my end.
To close the loop for everyone finding this, the issue is known by the sabnzbd team who are working on a fix, temporary solution is to downgrade libssl: