Hi priyankkaushik,
Got it. So you're on iOS 14.5.1 now, correct? If so, and all your apps are updated to the latest version, you may consider deleting some of those apps like Facebook and then reinstalling them to see if the issue persists.
If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open
Beyond that, you may consider backing up and then restoring to factory settings to see if the issue persists. Testing the issue with factory settings and without any of your data on the phone can help determine if there is a possible hardware issue.
How to back up your iPhone, iPad, and iPod touch
Restore your iPhone, iPad, or iPod to factory settings
Essentially, you'll want to set the iPhone up as new to test the issue. Then you can restore your backup at a later time after testing the device.
Take care.