All those things you listed simply confirm that a particular person bought a Mullvad scratch card. There's literally no way to associate that data with a particular Mullvad account. To do that they'd have to have a record of the card batch number and somehow have accessed the code underneath the scratch-off panel and then find a way to match those numbers against your Mullvad acct.

You're not wrong, BUT that's why Mullvad offers other forms of anonymous payment, the flexibility lets you be as paranoid as YOU want to be. You can pay in Bitcoin, or you can literally mail them an envelope of cash with no return address. Amazon scratch cards are just the most convenient option, and as always, you trade security for convenience.

You are buying access to a VPN not a nuclear warhead for the black market. The link between buying a VPN card and the code used in that card to link to said vpn activity which is also pretty well protected on Mullvad is not easily discoverable. Seems like a pretty reasonable privacy gap to me.

If you're a Mullvad customer then they already know your IP and from that they could identify you pretty easily. But that's true of all VPN providers, but they claim they don't log and I seem to recall them saying they don't keep a record of scratch off card numbers (why would they?). Either way you have to trust them and based on the fact they're totally open I do.