The same webpage I link shows that you can disable with a single option in the home page.
Google yourself how many times a disabled feature "accidentally" re-enabled(& tracked!) for providers' benefit. Throw Apple & Google un for the most nefarious "accidents". Or not... despite no proclamations of Moz employees posting (as of yesterday) this thread has the stink of astroturf.
I just want to set things straight. Bad mouthing Mozilla for something they have not done does not help discussing the decisions they take.
On tracking, well, you may always look the code. It's all client-side, I guess the most nefarious accident it could happen is you noticing the suggestion again and disabling it again.