Is anyone else having issue with screen flickering on messenger videos?

Salutations lakesh23, 

We understand that you’re encountering flickering when watching a video in a specific app. 

Is this the Messages app or the Facebook Messenger app? Since the issue seems to be app specific, here’s a few steps to begin with - 

Make sure your iOS is up to date Update your iPhone, iPad, or iPod touch

Make sure the app is up to date How to manually update apps on your Apple device

Restart your device Restart your iPhone - Apple Support

If a non-Apple app you can also delete and reinstall the app

Delete apps on your iPhone, iPad, and iPod touch

Redownload apps and games from Apple

Thanks.