Yeah, I'm also switching away. They're very sluggish on features. I went through all the rigamarole of setting up my own domain for the email service. Specifically with the idea that I could them automatically filter all my mail into folders by service. But, as it turns out, Protonmail has very limited support for sieve extensions. The crucial one is being able to create mailboxes from sieve scripts. So I can sort emails into folders, but I'd have to go create a bunch of folders, and make a new one every time I sign up for something. I'll be switching to fastmail, I think.
Though, if ProtonDrive became fast finally, I might still be convinced to pay a smaller fee for PD plus their VPN, which is completely fine for my purposes anyway(mostly just torrenting).
I think they are spreading themselves a bit too thin by trying to have an answer to every Google feature. I would have stayed if the core stuff worked. Would have been a lot better if they made some privacy focused API other apps could hook into and other providers could copy, and then we could create an ecosystem that replaces Google.