You aren't just charging your users "ad views". You are also facilitating 3rd parties tracking their online behaviour, and they certainly aren't agreeing to those terms when they first land on your site.
Could you be more specific? What "3rd parties" are tracking what "behaviour" of yours, and why exactly is it worth so much? And what do you mean by "you" in "tracking you"? Do they know your name?
In the case of photopea - as soon as I land on the homepage and before i consent to ANYTHING:
github
google analytics
facebook
stackpath
wikimedia
google adwords
google fonts
amazon ads
(a few others I dont recognise)
and, of course, the companies that you use to collect "consent"...
Even if i disable ALL the options on the "consent" module and reload the page, it STILL loads ALL of these. In fact, it seems to load even more! For example, I create a document, then it loads (in ADDITION to the above):
They are at the very least tracking that i visited your site. They are tracking the URLs that are active. As I click around and use the app, it is triggering more interaction with those services - so clearly they are monitoring actions/events too. This is just on YOUR site.
These networks are able to identify me by a cookie (and other techniques), so they can compile my activity on YOUR site into a log of my activities across multiple sites which they "provide their ads" on. They can absolutely identify you as an individual - google, facebook, etc, are ones that people have INTENTIONALLY given their names too, and many of these other networks sell/lease the data to others to allow them to provide their own identity link.
Furthermore, these 3rd party "scripts" have access to the entire page content too. They can read my email address should I register. They can even capture my password if they were so configured (or were in themselves hacked to do so).
Bear in mind i did NOT consent to any of this when I landed on your site, and even when i specifically removed "consent" via the form on your landing page, i was STILL being tracked by ALL those I mention above.
THIS is why people have blockers, etc. I dont mind if you have an image with a link to some advertisers product/service/whatever. What I care about it that my every action on your site is providing additional data for these companies to mine and build a secret profile of my browsing habits.
EDIT: I browsed without an ad blocker to compile this behaviour. I feel dirty.
The behaviour is what websites you visit. It is worth money because websites have topics which hints how they can better target advertising at you. Yes, they know our names because they can track us across every website we visit.
You aren't just charging your users "ad views". You are also facilitating 3rd parties tracking their online behaviour, and they certainly aren't agreeing to those terms when they first land on your site.