Vertical line on iMac screen - is it fixable or busted?

My iMac 2019 27" 5K Retina has a vertical line on the monitor that isn't behaving. It's definitely not software related, as a screenshot doesn't show it - hence the photo from my phone. My second monitor works fine, it's just the iMac screen that's busted. Might be the ribbon cable, might be a bad screen, I don't know. Anything I can try at home to fix it, or should this go to the Apple Store for repair?