vertical lines on my Mac Book Air(Retna, 2020

Hey SharonMc,

You can try running Apple Diagnostics to see if it picks up a hardware issue: Use Apple Diagnostics to test your Mac - Apple Support

Keep in mind, diagnostics may not be able to pick up on the display issue you've described. We recommend reaching out to Apple Support directly for help getting your MacBook Air inspected by a technician: Find Locations

Take care.

Hi SharonMc,

If you're having display issues you may want to try resetting your NVRAM to see if things persist. Here's how: Reset NVRAM on your Mac - Apple Support

If they do you can take a look at the Mac Service page here: Mac Repair & Service - Apple Support

If you need additional clarification you can always reach out for support here: Get Support

Take care.