I can't comment on the iOS client, but the Android client is what's primarily holding me back from switching to Protonmail as my default. The problem is that it keeps logging me out, for one reason or another, and to log back in I have to enter the password and TOTP code. That's a pain in the butt, and it makes it impossible for me to rely on for, say, airplane tickets.
Sure, I can do that again. My previous tedious interaction with your support department ended in this conclusion:
>Sometimes, when the ProtonMail app is updated to a new version and that update is bigger and more incremental, that could happen.
That's unsatisfactory. However it does not address the complaint I had at the time that every once in a while a notification appears that tells me I have been logged out, with no explanation. I don't know if that still happens, as I cannot be bothered to keep logging in on my phone. I'll give it a new try now.
Retrieving that quote for you meant I had to browse my Protonmail archive. I could log in via web, but for some reason your TOTP works differently from everywhere else: I have to enter it every time, and there is no way for me to "remember this browser". I could use the Bridge, but for some reason the Bridge, too, logs me out whenever it feels like it. Again, I have to enter both factors with no option to trust permanently.
Do you see how these paper cuts could demotivate me?