When inviting a user/member, you may get a message saying that the user already exists with those email addresses/mobile phones.
This happens when a member was already part of the team and the account can still be restored. At this point, no need to re-invite the member. To restore the account, simply go to the web app's Team > Removed Members > Select Name > Profile > Restore.
That's it! The member's account will be restored in your team. If you don't see the name of the member under Removed Members, please reach out to Support by sending an email to firstname.lastname@example.org.