Unsing an adblocker and other privacy addons actually help save data too

Do you uBlock origin installed?
It should block ads n unnecessary stuff to save some data.

You could filter/block images and audo/video/media(from all websites or some specific websites) if you want to save even more data.

$image,media,important
Adding that in your filter list would block all images and media, from all websites. You can adjust it for the specific websites that you want it to affect.

I mean if you really want to save on used data, I think blocking JavaScript would save a lot. Additionally, addblocker also saves a bit.