In 6.38.1 (and maybe earlier versions) when you perform a Reset Configuration and also a 5 second reset button on power on reset, the "/ system note" that was configured before the reset remains set. This is a bug, to me, as a reset configuration should remove all previous settings and set to factory default.

I wouldn't consider that a bug. I'd prefer that it remain set, so that I can continue to identify "where that router came from" if necessary.

If a poll were made, my vote would be "That's a feature, not a bug". Every use case is different...