Re:Firefox Focus – A new private browser for iOS and Android
by Manishearth on Saturday August 19, 2017 @10:49AM
(#15053666)
IIRC it is pretty anonymized already. I don't recall the details.
Also, Mozilla's privacy policy explains what Mozilla can do with the data. Generally it's not a matter of trusting the company as much as it is believing they'll follow their own privacy policy, which IMO is a reasonable assumption for most companies (including Facebook and Google, which use your data but do tell you about it)
Anonymised data would make me happier though :)