I've been MITM'ing my traffic to, among other things, strip ads and rewrite pages with things like custom CSS, ever since I discovered The Proxomitron over 2 decades ago. It does tend to get me profiled as a "bot" by CloudFlare and such, but there are not-so-trivial ways around that too. It also shows why things like remote attestation are hazardous for user freedom.
What works are browser based ad-blockers and app patchers like ReVanced. As my savings have gone up, I've relied more and more on just paying for ad-free services like YouTube Premium, Hulu, Netfix, and Max for the cases those 2 can't handle.