I just spent 2 hours figuring out what went wrong with my automatic upgrade.
My router just completely stopped working at midnight local time.
I noticed the Debian 12 upgrade and purged the iptables bits based on the earlier response, but nothing seemed to work.
Packets were no longer being forwarded.
Thanks to a Fedora bugzilla report, I finally have my router working again.
https://bugzilla.redhat.com/show_bug.cgi?id=2016864#c8
Hopefully, others will find this helpful.
How did this get missed?