Its starting to look like there is a FlexGate-II
This is now the third system posted here which noted the angle altered the screens display Vs backlight. I’m not sure if its the same short cable issue discovered with the 2016 models backlight issue.
It’s possible the issue is still within the T-CON board where the cables connect to from the LCD panel. The black plastic clutch cover which covers the area might not offer enough protection from a bang. Which while a weakness is not at the level of a recall.
Sadly, you’ll need a new display assembly to fix this.