Hi ritchey662,
Thanks for using Apple Support Communities! It sounds like you're having an issue with the display on your iPhone XR, and I'd like to do what I can to help out.
Your iPhone XR may need service for this issue, however, there are a couple if things you can try first.
Have you restarted your iPhone since noticing this issue? If not, go ahead and do that, as a restart can resolve unusual issues.
Restart your iPhone
If you're still seeing the flickering, you can try a restore of the iOS software using your computer. You'll want to back up your iPhone first, if you haven't recently.
How to back up your iPhone, iPad, and iPod touch
Restore your iPhone, iPad, or iPod to factory settings
Restore your iPhone, iPad, or iPod touch from a backup
If the issue hasn't been resolved, here's info on getting your iPhone serviced. iPhone Repair and Service
Take care!