app-store firebase ios react-native swift

iOS App Rejected – Guideline 2.3.1 – Performance

I just recently submitted my app to the app store. But app store has rejected my app and said

We discovered that your app contains obfuscated code, selector
mangling, or features meant to subvert the App Review process by
changing this app’s concept after approval to the App Store.
The next submission of this app may require a longer review time, and this app will not be eligible for an expedited review until
this issue is resolved.

We have not added any new third party library from last submission.
We are using react-native and firebase in our app from last 1.5 year, is this may be a reason to reject app.