According to Mentour Pilot, a pilot and YouTube content creator, plane windows have tiny holes that regulate pressure within the aircraft. The windows are constructed from three separate layers, with the holes located in the middle layer. The outermost layer is designed to handle impact and pressure difference, while the innermost layer does not have a hole to allow air to circulate around it.
The holes help regulate pressure and prevent forces from accumulating between layers. " The holes also minimize moisture accumulation between panes, making it more difficult for moisture to become trapped and fog up the window. Separately, Mrs Miva noted that flight attendants greet passengers for reasons beyond courtesy, though the specific reasons were not detailed.
Differences in pressure and temperature would otherwise start causing forces to build up between the layers, trying to bend them inwards or outwards.
That little hole is put there to allow air to flow through slowly and relieve that potential pressure difference.
It makes it more difficult for moisture to become trapped between the layers, and start fogging up your window.