Related to CDN stuff, there's LocalCDN, which I believe downloads the most commonly used scripts from various CDNs and hosts them locally, reducing the amount of tracking they can do as they aren't being pulled from the source each time.
I remember people recommending decentraleyes for some time and then I remember there being an argument against it. I don’t remember what the problem was though.
I happened across a thread on Lemmy recently that discussed the usefulness of certain extensions, and this "Don't Bother" section of the Arkenfox wiki was linked:
A lot of conventionally useful extensions like Privacy Badger, HTTPS Everywhere, Decentraleyes/LocalCDN, etc are apparently not necessary (at least in Firefox) if you have certain browser preferences selected, like Strict Mode/Total Cookie Protection.
I felt outdated cause I still run Privacy Badger and Decentraleyes in my Firefox environments, but it was nice to see that a lot of these "extra" features that used to require extensions are now options built into the browser (or Firefox, at least).