https://discuss.privacyguides.net/t/proton-mail-discloses-user-data-leading-to-arrest-in-spain/18191
Before that: https://www.wired.com/story/protonmail-amends-policy-after-giving-up-activists-data/
There are many, many more cases we don't hear about in media.
If you consistently connect to Proton via I2P or tor and don't link a phone number or tracable recovery mail, you're covering up at least some of the juicy metadata.