"Mozilla doesn’t sell data about you (in the way that most people think about “selling data“), and we don’t buy data about you. Since we strive for transparency, and the LEGAL definition of “sale of data“ is extremely broad in some places, we’ve had to step back from making the definitive statements you know and love. We still put a lot of work into making sure that the data that we share with our partners (which we need to do to make Firefox commercially viable) is stripped of any identifying information, or shared only in the aggregate, or is put through our privacy preserving technologies (like OHTTP)."
I happily switched to Zen on my desktop a while ago. Time to find a new mobile browser.