This complaint, in context of bright spots appearing on the iPad Pro 10.5 screen, appears here with some regularity. This is not to say that the problem is common, merely that the complaint appears to be common to the Pro 10.5 models.
Of complaints that have appeared within this community forum, the issue seems to focus upon bright patches (of varying intensity between affected devices) typically occurring in a region 1-2” above the Home button (as viewed with the iPad in the “Portrait” orientation - with the Home button at the bottom of the screen).
In context of physical construction, the iPad Pro 10.5 differed from other iPad models in that its main logic board runs along the central spine of the device - flanked by two equal sized Li-Ion batteries (a physical layout now inherited by the iPad Air 3). By contrast, most (if not all) preceding iPad models have their main logic board positioned along the right-hand side of the iPad, with a much larger battery/batteries occupying the majority of the remaining chassis.
The bright patches appearing on the iPad Pro 10.5 screen, where apparent, directly correlate to an area of the underlying logic board that incorporates the electrical connectors for the display - and the touchscreen controller. As such, as other iPads have a different internal layout, this is perhaps why we don’t see this observation occurring in other models.
Anecdotal comments (from reports appearing within this Support Community) suggest that when “inspected” by technicians, displays exhibiting this phenomena are generally considered to be fault-free - until such time as an inspection relates to a possible trade-in, at which point an affected screen has reportedly been described as having been damaged or defective, significantly reducing or eliminating any residual trade-in value.
The potential issue and its cause have never been publicly acknowledged by Apple.
I hope this is in some way helpful to you - if only in confirming what is known about this issue.
