“Enhanced Tracking Protection” is a poor name: it’s not just one thing, but has two modes: Standard and Strict. (There’s also Custom, which lets you go somewhere between the two, or restrict cookies even more tightly.)

The default is Standard. It doesn’t block GA. The cynic in me suggests they decided making Firefox disappear altogether from popular stats by default would have harmed them more than not doing it harms their users, or that the backlash would be too great for their liking.

Sources like Google Analytics and Statcounter are still chronically undercounting minority browsers and platforms, which are much more likely to block these sorts of things, and Firefox and Linux will be particularly heavily hit, but I’m sure the difference it makes isn’t as large as I’d like it to be.