sddm-greeter dumping core on Release after Dec 30

Hi,

currently running FreeBSD 13.1-RELEASE-p3 on an AMD- and renoir-based
laptop, everything ZFS.

my routine update of goes something like this:
- create a new boot env based off the current one, mount on /mnt
- pkg update on /mnt ("pkg -c /mnt update")
- activate new BE, umount it and reboot.

Since the end of December, I haven't been able to get a working desktop
that way, sddm-greeter reproducibly dumps core on me in the newly created
BE.
Following the approach above *without* "pkg update" results in a working
BE, so I conclude the procedure as such is sound.

Is this a known issue (initial research doesn't indicate it)?
AFAICT, sddm itself hasn't changed in a while (I haven't worked with ports
so far, I found "make extract" command online and did that, Changelog stops
in 2020)
How do I go about debugging greeter-core in /var/lib/sddm/ (meaningfully)?
I so far got a backtrace sans symbols ... I know my way around gdb, lldb
not so much, and both not on FreeBSD
TIA for any advice, pointer ...
Michael
-- 
Michael Schuster
http://recursiveramblings.wordpress.com/
recursion, n: see 'recursion'