@hellomacos - Let’s clarify things FlexGate was only an issue with the MacBook Pro’s 2016 & 2017 as these had a short cable so the backlight flex cable would fail.
Now due to the new method Apple used there is a higher chance of the cables running between getting damaged when the back edge gets a bang (black clutch cover). A second risk if getting an object caught along the inside just at the base of the LCD panel there is thin glass plate (Chin Plate) which covers the ribbons. What can happen is the object presses cracking the glass which then has a sharp edge punch’s into the cable damaging it (or a shard breaks free cutting the cable). So it’s important to inspect both areas for signs of damage.
The fact the chin plate was damage aims me to a damaged display cable!
This needs a retest this time closing the display with an external display connected (you can also use a magnet to fire off the Hall sensor if you know where it’s located). If the image is present on the external that proves the issue is the display assembly needs replacing. If not then the issue is within the logic board. I would still clean up and replace the chin plate to prevent future damage.