I restarted journald and all seems fine now. Will check the situation after a reboot to see if this was just a little glitch.
systemctl restart systemd-journald
Update: After reboot - same situation with logs stopping at this point in the syslog.
12/26/2023, 5:48:49 PM
systemd[1]: Mounted export-docs.mount - /export/docs.
12/26/2023, 5:48:49 PM
systemd[1]: Mounting export-docs.mount - /export/docs...
12/26/2023, 5:48:48 PM
systemd[1]: Mounted srv-dev\x2ddisk\x2dby\x2duuid\x2d31995d48\x2d98d2\x2d41e6\x2d91ad\x2deb9b6f6ce10f.mount - /srv/dev-disk-by-uuid-31995d48-98d2-41e6-91ad-eb9b6f6ce10f.
12/26/2023, 5:48:48 PM
(udev-worker)[712]: regulatory.0: Process '/lib/crda/crda' failed with exit code 254.
12/26/2023, 5:48:46 PM
systemd[1]: Reached target remote-fs.target - Remote File Systems.
Status of systemd-journald after system reboot - see below. At this point there is no logging to syslog after the log entries above.
Dec 26 17:48:40 rpi4 systemd-journald[170]: Journal started
Dec 26 17:48:40 rpi4 systemd-journald[170]: Runtime Journal (/run/log/journal/80ec49fe88324c98a44d189232c2bfe0) is 8.0M, max 75.8M, 67.8M free.
Dec 26 17:48:40 rpi4 systemd-journald[170]: Time spent on flushing to /var/log/journal/80ec49fe88324c98a44d189232c2bfe0 is 32.662ms for 435 entries.
Dec 26 17:48:40 rpi4 systemd-journald[170]: System Journal (/var/log/journal/80ec49fe88324c98a44d189232c2bfe0) is 104.0M, max 1.7G, 1.6G free.
Dec 26 17:48:40 rpi4 systemd-journald[170]: Received client request to flush runtime journal.
Dec 26 17:48:40 rpi4 systemd-journald[170]: File /var/log/journal/80ec49fe88324c98a44d189232c2bfe0/system.journal corrupted or uncleanly shut down, renaming and replacing.
After restarting the systemd-journald, the status messages are slightly different but not sure if this is an indicator of the issue.
Dec 26 17:56:18 rpi4 systemd-journald[3326]: File /var/log/journal/80ec49fe88324c98a44d189232c2bfe0/system.journal corrupted or uncleanly shut down, renaming and replacing.
Dec 26 17:56:18 rpi4 systemd-journald[3326]: Journal started
Dec 26 17:56:18 rpi4 systemd-journald[3326]: System Journal (/var/log/journal/80ec49fe88324c98a44d189232c2bfe0) is 112.0M, max 189.6M, 77.6M free.