Extreme high data usage by 3g-4g hat using ppp (UART)

I am using a Rpi 3b+ with Raspbian Buster 10 OS running. I am using the 3g-4gLTE hat from Sixfab with a qualcomm EG-25G modem in North America. But i am using AT&T network with a private APN. I am also using PPP connection over UART (SJ7&8 pads soldered). I used to previously use “sudo pon” to manually start connection after booting, but now I have set the connection to auto-connect on boot using the ppp_connection_manager that comes with the installation script.
I have started noticing that the data usage has gone up rapidly. Even though the actual data transfer to the cloud (i am only uploading some files at regular intervals from the Pi to the AWS cloud - so, I can easily know how much data I am using) maybe 70MB, the data usage on the SIM card is 10X as much.
Any pointers as to how to go about solving this?
We are planning to use this en-masse soon enough, and this can be a big issue in doing so.