Why does your Studio screen look so squashed in the vertical direction? Your Scale GUI looks matched to that screen size. It also looks correctly Scaled to the second video, but your overall screen height seems much bigger there.
So that’s what Scale does, is makes the GUI scaled to fit whatever screen size the player has (think different monitor ratios and tablet sizes).
If you make it a fixed dimension then it won’t fit all screen sizes. You’ve done what needs to be done, but you’re trying to view it at a strange screen size in Studio so it’ll look strange.
If you want it to appear smaller in game try viewing it full screen size in Studio and scaling it properly there.