Firefox自身が検索エンジンに送ってるみたいだね
Ubuntuの場合、firefoxじゃなくてubuntuになるだけじゃないの？

https://12bytes.org/articles/tech/firefox/firefox-search-engine-cautions-and-recommendations
When 'free' software isn't

I suggest reading The Mozilla Monster as a primer.

Have you ever wondered how Mozilla gets paid by the privacy-hating mega-monopolies like Google? Simple: When you use the default search engine plugins that are packaged with the browser, parameters similar to these are added to your search query:

client=firefox
name="appid" value="ff"
name="hspart" value="mozilla"