The forum

I don't understand how external monitors work with mac. I have an external WQHD display, which I have set as main display in settings and mac's screen as extended display. When I open Resident evil 2 remake in extended display I am not getting fullscreen in-game. There is always a bit of black border on side. Attaching the image. I have set the in game resolution to 2560x1440 and it's on fullscreen mode. I know the border is not supposed to be there because if I open the game after closing my Mac's lid, it opens it correctly without border. Also even if I get okay with 2560x1440, this resolution is making my mac very hot and if I decerease it, the black border gets wider.