How do I automatically align overlays on a Win10 computer?

Every time I move a File Explorer window over to my second monitor, this weird overlay appears over the screen and automatically re-sizes the window to fit in one of the highlighted areas. I also cannot simply drag the window to the top of the screen to make it full screen - it forces it into one of the smaller areas.

Can anyone identify what this is and how I can disable it? It doesn't appear to be part of the normal Windows Snapping feature.