I have a Nitro 5 (AN515-51-55WL) that we bought last November. A few weeks ago it started showing some flickering black horizontal lines that cover the bottom inch or so of the display. They appear when the computer is turned on, and usually start to disappear over time. They go away from the top down, covering less of the display, until I can't see them anymore. I booted to the UEFI / BIOS screen and still see the lines, so I'm confident it's not a software problem. The laptop has not been dropped or damaged.
For reference, it's a US warranty but we bought it overseas on a US Army base, and would be getting it fixed here in Germany. We have an extended warranty through the on-post store but I figured they'd probably like us to try to get support from the manufacturer first.