Line across screen on 2023 MacBook Pro M2 Max

the classic debugging technique for screen artifacts is to take a screenshot of some area of the display that includes at least a portion of the artifact. Then examine it carefully in large size, and move it around the screen.

¿is the artifact captured in the screen-shot?

--Yes, then the defect is in the Mac screen buffer

--No, then the defect is likely limited to the display itself.

This probably means that there is damage in your display. You can go to an apple store to ask them to check, and they can also repair it if there is damage on the display.

Mac Repair and Service - Apple Support

your appointment at Apple-owned store is free, in warranty or out. They can also provide a FIRM = (No Surprise extra costs) estimate of repair-by-replacement cost.

an Apple-authorized Service provider is free to charge an evaluation fee. I do not recommend paying US$50 to find out what you already are pretty sure about.