I am also unsure and that is also a reason why I have not disassembled my phone again for testing - that is my daily driver...
However, the dirt ("pocket dirt") seemed to be relatively high amount and I am also unsure which short end was it.
However, the problem was closer to the bottom end and when I have pressed the lower left corner, ghost touches have disappeared or improved for me for a while.
So I am also just guessing but as more people having the same issue, it would be more important to know the valid reason...
I still think it is most likely a display issue, but if the