We are sorry to hear about your experience with Samsung Galaxy S21+ having issues with the green line on screen. As well as the frustration you had when you brought the same device to the Authorized Samsung Service Center for repair, expecting it to be worry free. I feel and understand why you are worried for a device that you've take care so much. If my device is facing similar experience, I will be worried and frustrated too.
To ease your worries, support is a one touch away. If you're experiencing unusual behavior on your Samsung Galaxy S23 Ultra, you can send us an error report or ask us a question in the Samsung Members app. This allows us to take a closer look at what is happening. The data is anonymized and only held for the duration of the investigation. Find out more about how to send an error report here:
Step 1. Launch the Samsung Members app, and then tap the Support icon for more options.
Step 2. Scrolls and select Error Reports.
Step 3. Choose a category of your concern.
Step 4. Choose the frequency of the issue you are experiencing. Enter issue details or attach a video or screenshot. Then press Send icons to complete the report.
With the comments we received, I really appreciate the feedback you are sharing with us here. Thanks for your suggestions and appreciate the time and effort you put in to share your valuable comments. This helps us improve our products, apps, and services towards enhancing the Samsung Galaxy experience for all.
Should you need further assistance and guidance, you may contact us via our online Samsung Customer Care support channels below.
Members app as follows:
Step 1. Long press Samsung Members icon on Apps screen and tap Error reports.
Step 2. Tap OK on agreement popup to send system log data.
Step 3. Select Symptom category "Display".
Step 4. Describe the problem in details and SEND.
report via call / chat samsung support
bring to nearest authorized samsung service center in order to get diagnostic report