create a background frame for the bar and create the image to put over the bar, and make sure to add a uicorner with scale 1 and a uiaspectratioconstraint with aspect ratio 1
you should have 2 frames: a white one, and a blue one inside of the white one. actually, the white one should be a canvas group because I’m pretty sure it clips descendants that are outside of it. the white one should have a UICorner, but the blue one shouldn’t. the anchor point of the blue one should be 0,1, and you can have a script that adjusts the y size of it.
btw setting ClipDescendants to true on a regular frame wouldn’t work because it doesn’t clip by the corners