Mozilla has been a death by a thousand cuts over many years.

The first "user-enhancing" [1] in-browser ads ("sponsored tiles") were introduced in 2014. Pocket imposition was 2015 [2]. Mr Robot was 2017 [3]. Cliqz was 2017 [4]. booking.com was 2018 [5].

[1] https://twitter.com/dherman76/status/433320156496789504

[2] https://bugzilla.mozilla.org/show_bug.cgi?id=1172126

[3] https://www.cnet.com/tech/services-and-software/mozilla-back...

[4] https://www.zdnet.com/article/firefox-tests-cliqz-engine-whi...

[5] https://venturebeat.com/2018/12/31/mozilla-ad-on-firefoxs-ne...