"identifying" is the wrong word here--that's only possible if Mullvad stores a mapping between IP addresses and people, which according to them, a 3rd party audit, and a law enforcement raid they do not. It's also worth saying it's possible to use Mullvad entirely anonymously by mailing them cash, which I do.

Also if the threat model you're addressing w/ VPN usage is anything other than "I don't want my ISP to know what I'm doing" you need to use/do something else.