Third party apps, such as WhatsApp, may offer features that Apple’s native app, Camera, do not offer. This is not something easily, if at all, capable of being adequately diagnosed via posts, even if example photos are included. You need to have Apple perform diagnostics on your iPhone. It can be done in person at an Apple Retail Store or at an Apple Authorized Service Provider. You can also contact Apple Support and request remote diagnostics.
If you’re in the US, please call 1-800-MY-APPLE, or outside the US, consult the support articles below. In Canada, call 1-800-263-3394.
Contact Apple for support and service - Apple Support
Genius Bar Reservation and Apple Support Options - Apple
Explore Service Locations
Official Apple Support