Is removing "&nbsp" and "|" will fix the issue?

All elements with a class of nav-link should contain text that is the same as the <header>. It shows the error after clicking test. The texts in the links match whose in the header of sections other then I have &nbsp and | in my links so they would have between each other. I wonder if that is the issue, but I’m not sure.
Technical Documentation Page about HTML

Yes that was the issue.