Just look at Protonmail's own warrant canary before even listening to them.
Public consensus says in merit that they are good at what they can do/offer - but perhaps it is just security theatre. Or security theatre in the making.
To be simple .. they could be following a model similar to Germany's ISP/telco requirements in that they have to retain all connection timestamps and associated connection data. These cannot be turned off and are available to authorities. Logging of other details/metadata eg sites visited or files downloaded etc is not mandatory (unless requested by Swiss court) hence they do not log these details and state it clearly.
Having and/or knowing your IP / metadata is not the same as willfully turning it over.
Sure I can store it ... but would or/ would i rather I turn it over ?
Two entirely different things altogether. But with zero logs - nothing can be handed over. Not even a timestamp (with such a vague definition .. i doubt what they actually define as timestamps).
wrt to protonmail service they have your ''encrypted'' private keys - they have your data - they own you.
If they somehow obtained your passphrase (ie for the protonmail service) , they can retroactively read/turn over all your email correspondences.
Ghostmail and Lavabit .. for all the right reasons .. are/were better options and had been a prime base for many privacy conscious users until they were compelled to cease offering public email.
Even Scryptmail appears promising