I opted out with ublock origin and dns blocking.
[GA] Do Not Track Enabled; Google Analytics not loaded and tracking disabled
Edit: actually, this is them simply respecting your DNT policy, but Firefox also has a special blocker for these things. It also ships with some shims that unbreak badly developed sites which break without Analytics scripts present.> DNT is not widely adopted by the industry, with companies citing the lack of legal mandates for its use, as well as unclear standards and guidelines for how websites are to interpret the header. Thus, critics proport that it is not guaranteed enabling DNT will actually have any effect at all.
> After discussing this with several content blocking extension developers, we have decided to implement DNR and continue maintaining support for blocking webRequest