That is not really the same, Signal is a donation and Proton is a subscription where a monthly (or yearly) request has to go to the payment provider for your fee, for this you need to keep the payment information on file and linked to the account. Signal can say I got donated by someone but they do not need to keep this information linked to a specific user, just the payment record (that still has your cc/bank details on it) for tax purposes.

Yes they do, for tax purposes. With cash they can only say that an account was payed for by cash, which is not (easily) traceable to you as a person.

That is exactly what they did, the user used a credit card with their damn name on it, while Proton even allows you to send them cash money for the service.

The FBI filed a MLAT (Mutual Legal Assistance Treaty) request which was processed by the Swiss Federal Department of Justice and Police.

The Swiss gave a legal binding order to Proton to hand over information that they had, the only information that was handed over was the payment identifier.

I don’t get why people get hung up on a company complying with a legal order by their justice system, especially with Proton that could not hand over any more information.