It’s looking to be more an issue with the laminated displays. iPads with slight air gap between display and top glass (OG ipad air, 2018 iPad etc) appear to be free from spotlighting and/or bright spot which kinda makes sense when you consider that no actual hand/finger pressure actually touches or presses on the display itself. The laminated displays are subject to issues, imo, due to the display having bare minimal enclosure space between the display and components underneath. Without a separation of top glass and normal daily usage, the display is continuously pressing on the device innards and creating pressure points