Putting code behind a feature flag seems entirely fair and a good idea for developers of any size.
It's also a thing that can easily affect small developers; if your app requires logging into some existing paid account (enterprise software, a bank's app, etc.), the available features depend on what features the account has paid for. So as part of the review, you send Apple credentials for a test account that has all the features enabled. (Without a test account, they couldn't log in at all.)
It's also a thing that can easily affect small developers; if your app requires logging into some existing paid account (enterprise software, a bank's app, etc.), the available features depend on what features the account has paid for. So as part of the review, you send Apple credentials for a test account that has all the features enabled. (Without a test account, they couldn't log in at all.)