Interesting. Running this in Firefox on my M1 MBP, I get the following results:

  CPU: "Intel Mac OS X 10.15"
  Memory: undefined  
  Screen: 1512x982

The CPU result is doubly incorrect, since a) it's not an Intel chip, and b) i'm running 12.5.1 instead of 10.15.

The screen value is correct if you double it, i guess this is measured in points instead of pixels...