It is probably worth reading the clarifications made by ProtonMail [1] and their Transparency Report [2]. As a company based in Switzerland, it was clear to they could be compelled to do so and they never hid that fact.

IMO a breach of trust would be actually logging IPs by default and before a legal request is made.

[1] https://protonmail.com/blog/climate-activist-arrest/

[2] https://protonmail.com/blog/transparency-report/