Stuck pixel

There is no such thing as International Warranty on iPhone. iPhone warranty may be limited to the country the phone was purchased in. If you live in a country different from the country the phone was purchased in, you can schedule an appointment at your Apple Store Genius Bar, but Apple can refuse to service the phone there if bought in a different country.

That article was debunked and proven false LONG AGO. Apple has not changed iPhone warranty, locked or unlocked.

To see if Apple will fix your phone, you'll need to schedule an appointment with Apple and show it to them. But the warranty issue can cause you an issue if you bought the phone in a different country regardless of the false article you referenced.

OK. Then you need to take it to your Apple Store for evaluation and options. No one here works for Apple on this user to user only forum.