Step 1 with any project is to set the Video Mode before opening up any files in Shotcut.
After you have filters set in one video mode then change your video mode the filters do not auto-adjust. You have to adjust each filter/keyframe to the new video mode.
Example: Started with a 720p video mode.
Applied 1 filter for size/position of the 640x640 image.
Changed video mode to 1080p.
This is what happens when you change video modes after you set filters.
This is not a bug.