I have a samsung galaxy s9+ and sometimes I have this green horizontal line appear on my cellphone. I tried to take it to store as it is under warranty and they mentioned that since we cant see it now,we cant help you. If you see it next time,take a picture of it with another cellphone with imei number showing so we can ensure the issue and then apply your warranty. Seems a bit reasonable but not easy as it sounds, I know apple were alot more helpful when phone was under warranty.
Has anyone of you have any experience of going through Samsung warranty?