Does anyone know what's causing this line to appear on my screen whenever I unlock my S21 Ultra?

[ConorDavies]

Whenever I unlock my phone this line quickly appears on my screen, it only started very recently and is somewhat annoying. I have had my S21 Ultra for a few months now, I have never dropped it so I have no idea what could be causing it. It looks a lot worse in person than it does in this video. I should add that my phone is up to date too.

I also took a photo of the line...

[Sid_Karna]

You should visit service center while you still have warranty.

[AlenSony소니알렌]

Hey turn on always on display
Then put always on setting on aod then send video pls

Put aod to show always pls

[BVikram]

Those pixels are not getting refresh quickly. Most probably hardware or connector issue.

[cs-member13]

Dear Samsung Member,

Greetings from Samsung Customer Support!

We acknowledge your query and apologize for the same. We request you to kindly visit the service center for a physical inspection of your device. You can locate your nearest service center with this given link: https://www.samsung.com/in/support/service-center/

Thank you for writing to Samsung.

Warm Regards,
Samsung Customer Support