Unity Dual Monitor Size Bug?

Hey guys,

I’m currently working on a UI Based Game. While working on it I experimented with screen sizes, aspect ratios etc.
Now I found a weird behavior that I can’t explain. Maybe one of you can, maybe it’s a bug.

I’m mainly working on a 4k monitor, sometimes switching to my 1080p side monitor.

I created a new canvas besides my “main” canvas. I set the inspector values to be exactly the same as my old canvas. When dragging and dropping all Objects from my old canvas into my new canvas, all my GameObjects became insanely small.
When dragging my Unity Editor to the 1080p monitor, all objects shifted but were still very small. Switching back to my 4k monitor again, all object had the correct size and were filling the whole screen again.

This is probably some behavior caused by the Canvas Scaler, right? Can someone maybe explain what happened?

Might it be that your game window have “free aspect” as size or have a set aspect. Try setting it to a fixed size, for example 1920x1080?