Hey,
I use mullvad in combination with nextdns and am very satisfied.
The IP of the vpn is known when you login to an app or service but you are not the only one using that ip there are other people with the ip.
I change servers regularly , so I get a different ip.
If you look at what privacy features are built into mullvad and how they handle their customer data. you are pretty anonymous though.
You can pay with crypto, standard payment methods, gift card, send money by mail. Did you make a mistake somewhere with your payments.
Then just have another account number generated and you can work anonymously again.
Everything depends of course on your threat model.
I work with mullvad but there are other anonymous vpn services that are recommended.
Good luck 
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