Hey @zzrot . Welcome to the freeCodeCamp forum. I just tried the lesson here and I have the same extension. As soon as I disabled it, the code worked. Some extensions seem to interfere with the challenges, specially when they involve styling. Great that you solved it by yourself. Welcome again and happy coding.
Extensions that change the styling of a page will do so by changing the CSS and HTML of the page. That means that tests which check the CSS and HTML are likely to fail.