Where is the close button on checkout when customers access checkout via mobile device?
How can customers exit checkout on mobile devices?
Close button is not showing on mobile checkout pages
In mobile view, it is expected behavior for the window to not have a close button aside or "X" button from when they complete their checkout. If it has a close button in the top right then it means that the window is opening up within an iframe in the desktop view.
Going a step further, at a certain resolution, regardless of it being mobile or not, the checkout window loses the x button in the top right corner and the customer doesn’t get the option to close until they complete the checkout flow.