ads aren't chewing though my mobile data. I generally don't go to any sites with ads. The few times I open a link and it's covered in ads I close the link.
You might not be seeing visible ads but you're going to plenty of sites that are using tons of tracking pixels and making a lot of requests with and about various data you are providing. That might not be as data intensive as auto playing a video ad but it certainly makes a big impact overall.
Dunno, I have a 15gb/month through Mint and just use 1Blocker on iOS. I watch Youtube on 5G and use my phone like anyone else yet have data left over. So it doesn’t seem like there’s a lot of hidden data drain once you have a basic ad blocker.
Overtly consuming rich media from Youtube, Music, and Twitter dwarfs the data consumption of Safari.
Even your example of a tracking pixel is only going to be a handful of bytes.