User logins appear randomly on other parts of the app?

Like I said, you can unlink all sheets from user profiles, but I believe you won’t have access to the user profile anywhere else in the app. You would then have to create relations in all other sheets to get access to the user profile sheet. It sounds like you want to use user profiles, but not have it write new emails to the sheet? I would suggest letting it write the email, change your visibility conditions to look at a different user profile column that is only filled when they complete their profile, then instead of a form button to complete the profile, change it to a link to screen button and filter the screen that it takes you to by signed in user. Then the user can simply update the row with the rest of their profile information instead of writing a new row via the form button.