I am facing the same issue for Note 20 ultra. Just used for 1 year and 9 months. Screen was fine even when I checked in the morning. After like 20 minutes, when I checked my phone again, it suddenly had this green line. Restarted my phone, but it's still there. Samsung please help to fix this issue.
It seems this problem/issue happened a lot to Samsung 20 series (S and Note). I believe the latest version update of system eventually cause some part over loaded/powered and cause the screen defect to happen and damaged. It just my theory, I couldn't thought of any other reasons that cause this damage. Sorry this happened to your phone. You have to pay to replace it, unless you have proof of the system upgrade that cause this.
SAMSUNG INDIA has started to replace the screen FOC ... for several involved models ... i wonder if SAMSUNG MALAYSIA will do the same, many of the users actually faced the same issue, but was turned down by the Service Center. it is obviously a defect of hardware caused by software updates, cos in my case, the phone were absolutely FINE, the screen was un-cracked, un-dented and in its perfect condition, yet suddenly ... a green vertical line just slowly appearing ... sigh ... i thought SAMSUNG should really come out to address the problem
