Hi Chris,
Unfortunately we don't have a handle on the cause and fix for this error yet. It appears to have begun showing up on iPhone 12's and some iPhone 14's, but if you search online you'll find the majority of reports are of it occurring on MacBooks, particularly the newer Apple M1 and later silicon. Our resident Apple phone expert Alisha (@flannelist) has also looked into this; here's a link to their answer for a previous person with the same issue.
[post|772761|My iPhone 12 pro is restarting (AP Watchdog Expired) - iPhone 12 Pro - iFixit]
Our best guess is that this is a software issue and appears that it gets saved on a backup so even if you wipe the phone it can come back when you do a restore. Even so, it would be worth your time to put it in DFU mode and restore the phone back to factory settings. Run it for a while without restoring your backup and verify the issue is gone. If so, restore your backup and recheck. If it returns you may have to try removing apps to determine which one is causing the problem.
Alisha, have you run across any newer information regarding this one? Only thing I came up with is that SOCD does indeed stand for System On a Chip Daemon, which isn't all that helpful but does confirm that the issue is related to the CPU.