iOS 16

Try a forced restart.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)

If that doesn't fix it, contact Snapchat and ask them.

https://support.snapchat.com/en-US

You’ll find any grey or darker coloured screen will experience this issue in iOS 16. In my opinion it’s a software bug. I took my phone in for the same issue, they replaced the screen, then the next visit factory reset it, and finally replaced the rear system (this includes all the sensors, main board, battery, etc)… and still the issue persists. It started immediately after the iOS 16 update so I’m 100% convinced Apple missed this in their QA testing before releasing iOS 16.