Mozilla VPN is a rebranded version of Mullvad, everything is completely identical, only that Mozilla is using their own pricing model (which is naturally more expensive).

So yeah it's very good, but you better buy it directly at the source.

Edit: proof -> https://www.mozilla.org/en-US/about/legal/terms/subscription-services/

Iirc it is just a mullvad VPN reseller

Just use Proton, they just resell you Mullvad basically.