Patch 7.9: Borderless mode not fullscreen

So ive always played on borderless mode since i started as its easier to cmd+tab out as its instant whereas if im in fullscreen it takes a while to get the game back up weirdly. However since this patch borderless mode is no longer fullscreen it has a gap around a 1-2cm around the edge where everything on my desktop shows. The resolution is set right but it just seems to be capped to that much of the screen, anyone know how to fix this?