If you use Apple to log into Mob, you may have created an account using your Private Relay Apple ID (aka 'Hide my email'). If you can't recall which email address you used to sign up for Mob, it may be this encrypted email address (it will follow this format: '[email protected]').
Here's how you can look up this email address:
On your iPhone or iPad:
Open the Settings app, then tap your name to view your Apple ID settings
Tap 'Password & Security'
Tap 'Sign in with Apple' or 'Apps Using Apple ID'
Tap 'Mob'
The Apple Relay Email will be displayed under 'This App Received'
On your desktop or laptop:
Sign in to appleid.apple.com
Go to the 'Sign in & Security' tab
Click 'Sign in with Apple'
Click 'Mob'
You'll see your Relay Email under 'Hide My Email'