We are sorry to hear about your experience with the recent updates on your beloved Samsung Galaxy Note 20 Ultra having issues with the vertical green line. I feel and understand why you are worried for a device that you've take care so much, expecting it to improved after an update. If my device is facing similar experience, I will be bothered too.
Before you try out the below recommendations as to your solution, be sure to check if your device's software are updated with the latest version. Please check how to update your mobile device's software in the following order.
Step 1. Go to Settings > Software update.
Step 2. Tap on Download and install.
Step 3. Follow the on-screen instructions.
If that doesn't solved the issue, you may bring it to the nearest Authorized Samsung Service Center in your area. Rest assured that your device will undergo an assessment to pinpoint the its root cause. Our team of Samsung engineers and technicians will guide you and offer solutions to restore it.
or book an appointment with the Samsung Members app as follows:
Support > Book an appointment to set one.
Should you need further assistance and guidance, you may contact us via our online Samsung Customer Care support channels below.
Watch this. This says it all about right. However, I have given Samsung another chance. I traded-in my vertical line damaged Note20-U with another of their flagship phone. I hope they have corrected the flaws, most especially the "SNAPDRAGON 8 Gen2 for Galaxy " now installed, wc so far never overheated this phone, not once for 4 months of use. Let's see further on..