What makes me not want to use it is I assume Mozilla has a legal presence all around the world.
Two huge reasons people use VPNs is piracy and saying things/accessing content that's not legal in their country. If that company has a legal presence in your country, then they'll hand over that data to the police should you criticize the wrong person or download a movie without permission. At which point a VPN becomes kind of pointless.
It depends on whether the company keeps records or not. They can't turn over records they don't have.
how is that any different from any other VPN provider?
The only time i use a VPN is when i'm traveling and I don't trust "free coffee shop wifi"
I probably won't use Mozilla's offering, because i want any VPN to cover the whole system, not just the browser (correct me if i've made a bad assumption here)