You have to write real category descriptions, there’s no escaping that.
Google thinks your site is low-effort, and you’re reinforcing that sentiment by trying to skip making the minimum required effort when creating new categories. Each category needs a unique and distinct description. It’s an opportunity to provide content for both your users and search engines which crawl the site.
Again though, as I’ve already pointed out several times and others have echoed, this isn’t a Discourse-related problem. An SEO community would be far better placed to help you with Google issues.