paprikatongue The example that springs to mind is I'd heard of a French activist being arrested with the help of proton.
I don't know, this seems more like a story of the activists having bad op sec, if they were really trying to remain anonymous from legal authorities.
Protonmail in this case did what it claims to do, which is end-to-end encrypt the contents of one's emails, so there is no way to hand over that information. But it is well known that email still has a lot of metadata, like IP addresses, that can be used to track people. There's no way for Protonmail or any email provider to get around that.
Protonmail however does operate an onion server so you can acess it via Tor and that service existed long before the activist in question started using Protonmail. If they had followed Protonmail's own guidance about how to have greater anonymity, it probably would not have been possible for Protonmail to identify their IP addess when compelled by a legal Swiss court order. Or the activist could have used a VPN and probably protected themselves.
In any case, Protonmail is not an anonymity service. It is a service that protects the contents of your email with encryption. And even then, that depends on communicating with other users who are either also using Protonmail or who use PGP. And Protonmail also blocks some of the common tracking tactics used for marketing purposes in emails.
You are not going to find an email service that can provide you more than that. There are inherent limitations to email, in terms of obscuring one's identity or location.
Honestly, if you think you may become the target of a court order, as in this case, then you better be very careful about your op sec, because there are a lot of ways to reveal one's identity. It's going to take way more than what email provider you use.