lines on screen

Does the line appear in other areas of the screen?

Does the line appear in another web browser or in other apps?

Does the line always appear the same?

Take a screenshot of the line, then open the screenshot in Preview. Move the Preview window around. Does the line in the Preview window move around or is it even seen in Preview?

How to take a screenshot:

https://support.apple.com/en-us/HT201361

Have you tried rebooting the computer?

Can you post a picture of the issue?

I have tried to reboot us by pressing the PR command control. It restarted twice but looked just the same .

I'd like to get a technician to look at the screen.

The lines are the same for a while and then it begins to flicker.

The Apple Stores outside of China are still closed this week, but an AASP may be open. Otherwise you will need to wait a little while.