What Causes Flexgate
Basically, it comes down to cables. iFixit notes that, in newer versions of the MacBook Pro with Touch Bar, Apple opted to change the type of cable it used to connect the display to the display controller board.
Specifically, new MacBook Pro models use a thin “flex cable” to connect these two components. Reportedly, this cable is prone to stress and fracturing when the MacBook Pro’s lid is opened and closed repeatedly — which is, of course, a normal and intended function of a laptop.
Previous MacBook Pro models used more durable wire cables that actually could be routed through the display hinge. According to iFixit, that helped to “mitigate the stress of repeated openings and closings.”