What is noise in wifi? Noise is a RF signal that cannot be decoded as 802.11. NOISE is any signal (interference) that is not WiFi traffic such as cordless phones, microwaves, radar, etc.
This means there is a transmitter using that freq, but is not using one of the 802.11 understood encodings.
NV2 or Nstreme would have been recognized by a Mikrotik device. Others do not understand that signal.
A camera or alarm system may use this, any IOT device, a drone, home automation .... just anything that is sending not 802.11 compliant signals.
( Would 802.11ac recognize all 801.11ax ??? Normally 802.11 is backward compatible.)
Does Snooper (with "Receive errors " allowed) reveal any MAC address?