In terms of marketing understanding, 1YAUs < 28DAUs < 7DAUs. Machines get re-imaged, apps get re-installed, low-enagement users are not a great indicator of value, etc. etc. etc.
Eh, this is the usual split: care about (and try to change) 7DAU, report 28 or quarterly as those #'s are usually an impressive multiple and are easier to re-publish year-on-year without having to explain, e.g., seasonal variance. Don't think Mozilla is doing anything unusual.
& Web Standards TL; Blink API OWNER
Named PWAs w/
DMs open. Tweets my own; press@google.com for official comms.