Haha... Same for all phones, bro.. After updating, I got white lines... when I asked Sri Lankan samsung services center they said I must pay for new display.
I also got a white line middle of the display while I was using the phone... still no solution for this... but I read in some thread that it's happening because of heat under display.
Same here, white line appeared in my Samsung Galaxy A71 phone yesterday. I'm sure my phone didn't fall.. this just appeared while I'm using it. I also got a reply from them to change the display as an answer from them!
Green Line and White Line issues are common problems in Samsung phones. Some got it after updates, and some got it due to heat under display. But still, the company is not accepting it as a common issue.
