This might mean that you have chosen to login to the app with your Apple-ID but not share the email with us.
In this case you can follow this guide:
1: Go into settings and click on your Apple-ID
2. Click on Password & Security
3: Click on Apps using Apple ID
4: Click on GeoGuessr
5: Find your email that you can login with (or send us an email if you wish to change it to something else)