If I want to opt out, I can only opt out by disabling all usage telemetry according to the official doc https://support.mozilla.org/en-US/kb/share-data-mozilla-help-improve-firefox . That means that my usage habits and the usage habit of all people that do not want to share their search terms with firefox, i.e. all somewhat privacy interested people is just thrown into the void. For future browser decisions, this means that the browsing behavior of a whole group is neglected. This makes me sad.