Google have had massive changes to the Debug page. They have pretty much removed all the information including the rich cards troubleshooting.
The only thing that remains is a “Useful testing tools” section, now divided in to webmaster tools, anonymous tools and “other” tools.
They have also introduced a section on how to use tools to test locally hosted pages with a tunnel.
The best thing they have done is moved and reworded a tip on crawling times:
Remember that Google does not crawl your page immediately after you publish a fix. Therefore Search Console (and Google Search) can continue to show an error for a page that you have fixed until the page is crawled again. You can sometimes request an expedited crawl, for instance using the Fetch as Google tool, but in most cases it takes a few days to notice changes in your pages.
People still won’t read this and will still head over to the webmaster forums to complain that errors are still showing in the GSC after they fixed it.. but at least it’s easy to point people to this.