huge window when opening/inserting files

Hi all,

I hope I manage to explain my "problem" (first world problem actually) properly. When an app or website wants me to open or insert files the window that than appears is huge, almost the size of my whole screen. This is the last couple of weeks. Before that a smaller window appeared when I open/insert files.

Does anyone know how to change this? How can I make the window smaller?

Kind regards,

Hugo