problem red vertical line

Take a screenshot of the whole screen.

see > Take a screenshot on your Mac - Apple Support

If it shows up in the screenshot, then that points to the GPU.

If it does not show up in the screenshot, then that points to the display.

Either way, you need to make a service appointment at your local Apple Store or AASP.

This is likely a hardware failure, I would suspect the GPU is failing. Please take the computer to your local Apple Authorized Service Provider to be tested. Also, when posting please provide MUCH more complete information otherwise we have to guess. The information in the following link is good for first time posters:

Writing an effective Apple Support Communities Question