Moving window to second monitor causes window to change size

On Windows 10, I have a PC with 2 monitors of different resolutions. If I drag my glfw created window from first to second monitor it suddenly changes size when it gets exactly half way onto the second monitor. Is this a bug, or am I doing something wrong?

That sounds like per-monitor DPI scaling. Did you set the GLFW_SCALE_TO_MONITOR window hint? What version of GLFW are you using?