The text you quoted sounds like a reasonable and normal definition of a sale to me. i.e. transferring to another business in exchange for something else of value.

So yeah, Firefox previously promised not to do this, "not ever", and now they say they need to do sell your personal data "in order to make Firefox commercially viable".

But hang on a second... Firefox is not a commercial product. So making it 'commercially viable' is highly questionable in itself.

It's a shame that Mozilla's current leadership is more interested in self-enrichment than in the past. But Firefox is still the very best option by far. I hope that the Ladybird project becomes strong the future, if for no other reason than pressure Firefox into staying good.