I have green line on my iPhone 11 Pro Max.

I bought the iPhone 11 Pro Max for 6 months now In cambodia . In the first three day of using it , it showed the green straight line on my screen for about 2-3h then it disappeared by itself. It happened 10th times already. When I asked the store that I bought they keep saying my screen is broken while I always keep it safe. Also now it showed the green line on my screen for 4days already. I don’t know if you have any solution to help me, because when I searched in the discussion of Apple show that it’s Apple fault on display. Also they will change display for free since it’s really cause of green line. So , how can I change my display in cambodia since there’s not Apple store here.