I'm not saying Proton was right or wrong to hand over data, who knows how much if a fight they really out up, but it seems more like an OpSec thing, where they found the account because they used that email to create a user account somewhere that they then posted about being a part of this group rhe FBI was going after.

I'd say your best bet to avoid this would be to create a free account that doesn't have any payment info and doesn't use your premium account as a recovery method of any kind if you're going to use it as the email associated with a social media account. Or like someone else mentioned, if there's an anonymous payment method, always use that.

Again, not a great look for Proton, but doesn't really go against any of their claims as far as data encryption is concerned. Not sure if they could encrypt that payment info.