Some HTML tags like <big><small> and <em> are not stripped from the category description when displayed for instance in the category dropdown and in the category settings.
It seems like this does not affect any security related tags like script and style so it’s a minor thing.
The category-chooser component used the category description instead of the description_text, which strips HTML. We allow HTML elements on the description because we use it to generate the category definition topic. Should be fixed by: