Choosing “Hide My Email” signs you in with an Apple private relay address instead of your real email. If you already have a Tableful account under your real email, that creates a separate account — we can't merge them automatically.

Apple asks only once. To change your choice, go to appleid.apple.com → Sign-In and Security → Sign in with Apple → Tableful → Stop Using Apple ID, then sign in here again — the share-or-hide prompt comes back.