I set the following in my user.js to disable this kind of thing. It keeps my default search engine suggestions but disables all the junk. Strictly speaking I think the last line is technically redundant as quicksuggest.all=false should disable .sponsored as well but no harm in being explicit about it.
The title has been editorialized & elides the change is regional rollout rather than introduction of the functionality itself (been discussed for years at this point).
It's probably easier to search for lists of things to disable in Firefox than go one per post anyways. One of the nice things about Firefox (other than the relative amount of these things) is the knobs to remove them usually exist somewhere for you to pull.
It's annoying, but thankfully it's a single checkbox in the settings to disable it (uncheck "Suggestions from sponsors").
https://support.mozilla.org/en-US/kb/firefox-suggest
It's probably easier to search for lists of things to disable in Firefox than go one per post anyways. One of the nice things about Firefox (other than the relative amount of these things) is the knobs to remove them usually exist somewhere for you to pull.
I use Firefox because I believe in an alternative to Chrome, but they make it fucking hard to love Firefox.