IOS 18.2.1 on iPhone 13

The update is unlikely to be related to your issue as updates are supposed to provide bug fixes.

Please try a Force Restart.

• Press and quickly release the volume up button.
• Press and quickly release the volume down button.
• Press and hold the side button until you see the Apple logo 

Force restart iPhone - Apple Support

After either the vertical green lines will go away which means it was a software issue or if it doesn’t go away…

This is likely a hardware issue in which you need to make an appointment at your nearest Apple Store’s Genius Bar or Apple Authorized Service Provider for diagnostics and evaluation.

Genius Bar Reservation and Apple Support Options - Apple 

Try a Forced Restart, but if it doesn't help, you'll need to schedule an appointment at your Apple Store Genius Bar for evaluation and service options --> Force restart iPhone - Apple Support (CA)