It is the MZLA Technologies Corporation a subsidiary of the Mozilla Foundation. Firefox is developed by the Mozilla Corporation a wholly owned part of the Mozilla Foundation.
Yes. Mozilla was originally only the non profit, but it was ruled that selling the search rights violated nonprofit status. So they paid a couple million in back taxes and had to spin off a corporate entity that's fully owned by the nonprofit.
It's a "we want to sell something, but non-profits aren't allowed to do that" trick. And it means the for-profit subsidiary has to pay normal taxes.
OpenAI is structured the same way, so they can sell access to their models. At least until it switches to being entirely for-profit, if that is allowed to happen.