The way I understand this is that your data is e2e with the mullvad key, meaning Obscura can’t see what you’re browsing. All it can know is who you are (because of your IP address). Mullvad is the one who sees what you browse (if they were to log) but doesn’t know who you are because the traffic comes from Obscura’s server. That’s the difference between Obscura’s VPN and going straight with any other VPN where they can log your IP along with your browsing.
Imo, that extra anonymity and speed loss are not worth the extra expense, but it really depends on your threat model.
The way I understand this is that your data is e2e with the mullvad key, meaning Obscura can’t see what you’re browsing. All it can know is who you are (because of your IP address). Mullvad is the one who sees what you browse (if they were to log) but doesn’t know who you are because the traffic comes from Obscura’s server. That’s the difference between Obscura’s VPN and going straight with any other VPN where they can log your IP along with your browsing.
Imo, that extra anonymity and speed loss are not worth the extra expense, but it really depends on your threat model.