How to handle schema change when deploying to ios app store

Hi there, how can we handle schema changes when in production, we are trying to upload our app to the app store and we are using flexible sync , but we are confused on when we should deploy our new schema changes , because we have two environments (Dev and production) , and whenever we want to make a schema changes we want to deploy those changes to the client.

we have 2 things we need to track the client schema on device and the backend schema on Realm backend the schema needs to be equal to client schema otherwise the client will get a sync error,

If we push the app to the app store for a review before we deploy to realm then the reviewer will have the latest client schema but the backend schema will be different on realm backend
if we deploy the backend schema first then the clients will have sync issue until they update
so we need to find a solution around this.

what would be the best approach to handle this problem ?

Thank you.