Probably internal tests?

The software identifies the hardware, performs the benchmarks, and sends the heading and results to the Geekbench DB. Somebody who had the machine at hand must have run it.

I thought they were skipping the M6 pro chips (or is that just the max and ultra?) to accelerate AI focused M7.

Internal leaks, these happen frequently. Employees have access to these devices for months prior to launch. Someone ran a benchmark and uploaded it on a machine they weren't supposed to.

How does Geekbench even verify what CPU I'm using? Couldnt you inject forged data and add a even faster M100?