Most people do not know that Proton (Proton Pass & Simple Login), only allow ONE alias per third party website. It is against their ToS to create more than one alias for the same website.
It’s a terrible rule that I’ve talked about here, here, and here.
It is essential for privacy to be able to have multiple accounts with the same website to compartmentalize your life. But Proton is against it, and on top of that they pretend they are not in their marketing.
That’s why it’s better to go with Addy.io who allow you to create multiple aliases for the same website.