Hole in PCB due to corrosive reaction?
It's unlikely.


The hole is very nearly circular, and has smooth edges, indicating the hole was deliberately drilled.
Somebody has added thin wires to try to repair the damage, indicating the defect was found and "repaired" before the product left the factory.


Most likely the hole is meant for mounting the board into the housing. The damage to the surface layers is a fabrication defect that they tried to fix rather than scrapping the board.

Edit: As pointed out in comments, another possibility is that the hole was drilled  deliberately to remove some incorrectly designed wires, and then the added wires you see were added to replace the connections broken by the drill.