ProtonVPN is the same company as ProtonMail. The company has had a good rep, reminds me of Lavabit.
Isn't there at least some controversy about that (perhaps it's only a disgruntled competitor who jumps on every second post I see mentioning them, but I'm 99% sure I've seen a few questions/accusations levelled at them...) Having said that - seeing them vouched for by the Mozilla Foundation seems to be a significantly better indicator of their trustworthiness than this post from a day or two ago: https://news.ycombin…
I fully agree that ProtonVPN seems like a poor choice, considering all the controversy around them, especially when its backed up by that much evidence. Mullvad, Private Internet Access, TorGuard etc. would have been a better choice, but perhaps Mozilla didn't want to look like it was picking sides among 'established' VPNs..