First off, if they were real about privacy they'd include uBlock Origin by default (and why not HTTPS Everywhere for good measure as well). Their current tracking "protection" is an absolute joke that explicitly whitelists Facebook and Google, the two biggest offenders when it comes to privacy: https://news.ycombinator.com/item?id=20112398
They should also remove Google Analytics from their website, or at least the pages that the browser will automatically load on first use or after an update. While Google claims they have some special relationship with Mozilla regarding this and they won't use the data for any other purposes, it's hard to trust them - Facebook for example used to say that phone numbers would only be used for 2FA and yet somehow they ended up being used for advertising.
They should also make the telemetry opt-in instead of opt-out like it is now. Their current way of doing it might actually be in breach of the GDPR, as any non-essential data collection and processing must be opt-in.