You say you use ProtonPass with a free Proton account? Do you know if they have a limit for creating these new emails? I've seen ProtonPass advertised but I just assumed it was a premium feature. When I say its tedious, its because when I create new ProtonMail accounts you first have to verify it with another non-Proton account which I find a bit annoying as I dont use services like Gmail etc , but more importantly, Proton has been blocking signups on newly created emails (if you just created the email and then use it to verify a service sign up it gets blocked).