I’m bumping this because I see other posts have modified subject lines and I think this one got missed. Turns out this only happens when editing the header template. The ‘preview’ of the header is fine when editing pages and other templates.
Is your screenshot of code from within the builder, or front-end? This issue is happening within the builder, when editing the header template.
Please refer to my previous screenshot for what happens (Markup 2023-09-01 at 04.10.37.png - Droplr). Since the class is applied to both the li and li > a, it’s styling the list item and the anchor, so padding is doubled, border treatments, etc. are all doubled causing an inaccurate representation of what the header will look like on the front end. It makes editing a challenge.