I was unsure of how Protonmail's acquisition of SimpleLogin was going to work, but the details are clear now. If you have a paid protonmail account, you will get premium SimpleLogin for free, meaning unlimited email aliases. If you have a free protonmail account you can link a free SimpleLogin account and get 10 free email aliases. I was paying for both so now, I will only be paying for Protonmail. I highly recommend both services and spending a tiny bit to support privacy respecting projects.
If you're unfamiliar with SimpleLogin, heres the idea. Everytime some website asks for your email, you click the SimpleLogin extension, and it generates a new email alias. You click your Bitwarden extension and save your email and generate a passsword. You fill out the "create user" info by clicking ctrl-shift-L (autofill password for Bitwarden) and you're good! Emails sent to the alias go to your normal email inbox, but if you start getting spam to your alias, you can just kill that alias.