iPhone 12 SIM issue

I bought a guy's iPhone 12 yesterday. Before accepting it, I checked the Carrier Lock item in Settings and found the display said "No SIM restrictions." (My old iPhone likewise had no SIM restrictions)

The old iPhone and the new iPhone were up to date on the same software version. I activated the new iPhone by a wireless transfer from the old iPhone. Now my old phone and my new phone both have SIM lock status. I was never able to clear the lock and activate the iPhone 12. Verizon Wireless currently has a one hour wait time in its stores here, so I haven't had an opportunity to have VZW troubleshoot it. I was able to restore my old iPhone from iCloud, but now it still has a locked indication.

How can one determine the source of the lock and clear it?

Thanks,