That’s because in studio your resolution is slightly smaller, to see how it would look like in-game when you’re in studio, do the following:
Click the device icon top right, change the device dimensions to whatever device you’re currently using and instead of “fit to window” use “actual resolution”, that’ll show you how the UI will appear in your game.
It’s also recommended to design UI using scale, since then it will scale down/up according to the resolution of the native user’s device (smaller for phones, larger for computers etc.).