@Sh4d0w_H34rt @protonmail @Tutanota they’ll probably do it the same as Proton.
As far as I know user1@protonmail and user1@proton.me go to the same inbox. If you were a new user after the rebrand you’re only allotted user2@proton.me
Would assume something the same here… where older uses can still retain and use the user1@tutanota but newer users “only” have the new(er) domains.