I could trust them more than random custodial or closed-source web wallet out there, but generally using web wallet isn't good idea. Besides, i feel they offer too many services these days even though i hear complain about poor support for Linux.
Is Protonmail still popular? I remember that there was a boom in 2016 and almost every privacy-oriented guy was using it. Is the situation still the same? I haven't seen a proton mail address recently.
I also don't know how popular is it these days. But it's still frequently recommend to people who want email with better privacy (usually better than gmail).