What, sending bitcoin? That's not really a feature of Proton Mail, rather it's a feature of the wallet that happens to be able to send bitcoin via email (I suppose so that the recipient can then transfer the funds to a bitcoin address of their choice unless their email address is already linked to Proton Wallet).

Even if you'd consider this a feature of Proton Mail, how does this have higher priority than a proper iPad/tablet app, or the ability to add a .ics attachment directly to my (default, non-Proton) calendar without having to manually download the .ics file, open it with a file manager and then add it to the calendar? Filtered views (for example: view unread and starred messages but nothing else in one list)? A somewhat usable offline mode? The list goes on, and that's just Proton Mail. Proton Drive still lacks a native Linux app (I know there's "support" for Proton Drive in rclone, but that's hacked together because Proton doesn't even provide official API documentation and stability commitments).

I'd rather pay for the individual services that I can actually (somewhat) use, like Mail (even though it's not great), but their Mail only tier severely lacks in features (only 1 custom email domain is my main problem). If they'd then commit the financial resources towards improving the service being paid for, that'd be great.

Maybe they should get search working first? Or just contacts sync?