Upgrading to 12.5.1 from 12.5—iMac M1 hardware

I check for updates, and I am being told the machine is up to date with 12.5. There is a package I wanted to test, and the third-party software requires 12.5..1. A search tells me that 12.5.1 was a recent (important) security update.

What am I missing? The hardware is about 14 months old, so it feels new enough to be supported. Is it possible that my specific machine does not need the 12.5.1?