Recent versions of mobile operatig systems like Android 10 uses a new privacy setting to avoid tracking, randomizing the last 3 bytes of the device MAC address.
To override this, a new
mac_randomizer_mode option has been added to the MQTT script. This mode marks as the same MAC address if the first 3 bytes of the MAC address appears in the last 15 minutes (you can change the threshold). It’s not a perfect solution, but the chances to get the same first 3 bytes (often related to a brand specific model series) in a short time window within a few meters distance from the detector device are very few indeed.
Check out the esp8266 people counter project repo for more information.