There can be multiple reasons why your FnO Income Proof was rejected.
To know why your Income Proof was rejected, kindly check your registered email. Here is an example of an email for your reference:
If you are unable to view this email in your inbox, please check your spam folder as well.
If your income proof is rejected, you can proceed to re-upload from the app or web or by clicking on the "Upload your Income Proof" button in the email.