ARGON ONE M.2 - I have an extra pin on my M.2 base board what's it for?

They added it, but for me, it had the unintended side effect of not allowing the Pi to boot at all. Once I covered the pin with tape, it started booting normally. I have the M2 Sata version with a teamgroup 256 m2 sata drive.

The info on that other behavior is on this thread: here