I have developed a MacOS app with a toolbar in Catalina running on a 2013 Macbook Pro and the toolbar height is sufficient to show all icons in half the screen as shown below:
However a user has reported that their toolbar appears as shown below, where the toolbar is reduced in height and the icons so widely spaced that some are not shown and appear as pop-up menu items which are disabled. Is this a consequence of using a newer OS than Catalina? Is there a way of increasing the toolbar height so that all icons are shown in newer versions of MacOS?