This is what the right-click menu looks like in Firefox on macOS [1]. Compared to the right-click menu from Safari on the same machine [2], you can see several differences. The most notable one is that the Firefox menu is not theme-aware, rendering a light-themed context menu even though the OS is in dark mode. Next, the padding around the menu is incorrect compared to a native menu. It also looks like the font is maybe a different size. Finally, the drill-down arrow on the Firefox menu doesn't match the native one.