I meant to just post this in a related topic but could not find the post I was looking for, mods feel free to move this for me.
It looks based on these two ([1] [2]) reddit posts that Proton is now adopting Simple Logins policy when it comes to what happens to your alias emails if you downgrade. I know these differing policies have caused some confusion in the past.
Thanks everyone for the feedback in this thread. We’d like to let you know that the SimpleLogin policy will start to apply to Proton Pass downgrades as well, in the upcoming period.