Mozilla, reading the room extremely well, seemingly just recently flipped the switch to enable-by-default sponsored weather results from AccuWeather in every new Firefox tab you open. Clicking "Learn more" takes you here, with zero information on if your location is sent to AccuWeather every time you open a new tab: https://support.mozilla.org/en-US/kb/customize-items-on-firefox-new-tab-page
Probably only noticed because I normally have a blank new tab page but this showed up after updating Firefox!