When you are using your mobile data you want to count your precious bytes. And in my case I don’t want to install any 3-d party apps for such a simple task.
Luckily on MacOS you have
nettop -n -m route -k rx_dupe -k rx_ooo -k re-tx -k rtt_avg -k conn_att -k conn_est
…simple like that. It will provide you with enough statistics without any additional noise
You may read more about nettop here