Not really. It is more correctly a "reference" pin for 5 V devices, but principally it is the proper way of powering the Arduino since it is a direct connection to the 5 V line for the ATmega chip and the USB interface.
Of course, when you use the USB interface you feed - again , 5 V - into the USB connector and you can get something approaching 5 V from the "5V" pin except that there is a diode in between, dropping some fraction of a Volt and with (generally) a 500 mA current limitation. And if you are not connecting via USB, the USB chip is wasting your battery power; it would be better to use a Pro Mini.
"Vin" should be strictly avoided.
Finally, a Chinese clone may or may not actually have a 3.3 V regulator capable of powering a NRF device.
If you are powering it via 5 V, you have a 3.3 V regulator regulating down from the 5 V line. Except for clones deriving 3.3 V from the USB chip which have a very limited current capability.