Disabling signups for database connection not working as expected

In my setup, i have one WebApp and a Mobile app (iOS). The purpose of the webapp is to onboard/signup users that are going to use the mobile app. I want the signup in the webapp to be passwordless (sms), and the login in the mobile app to be the same way. But i want to prevent signups from the mobile app.

What i did so far, was setup two diffferent database connections. One (used by the webapp) that allows new user sign ups, and the other (used by the mobile app) that disables them.

But, that’s not working as i would expect, as i am still able to create new signups in the mobile app.
Am i missing something?

I am using the Auth0 Swift SDK.
Thanks in advance