Set the Navbar layout display to Flex Horizontal, align Centre.
Also, your Menu Button (and icon) have a lot of properties applied throughout the breakpoints (paddings, margins, width, height, max width/height, typography sizes etc.). This is over-complicating the layout and forcing the icon off-centre.
Try a simple width/height setting for the button eg. 30px x 30px and remove the other settings which are applied - this will horizontally align your icon.