The option is greyed out, YET checked. I cannot change it at all.
How do I force Firefox to uncheck it? I feel like a boomer asking this, but…
I tried using the about:config to put the boolean of
browser.newtabpage.activity-stream.system.trendingSearch.enabled
to false, but nada.


I suggest that you should use SearXNG, It is not a single provider but multiple instances. I use it too. Its good for privacy but may not be accurate all the time