The new FS for 'Lupus' not only pulls in content from the ranking page (Mayo Clinic), but also appends this "Symptoms" call-out, which is *not* taken from text on this page.
The word "pericarditis" appears nowhere on the page. 🤔
Also, I'm seeing multiple examples Featured Snippets appear on desktop, but refreshing and switching to a mobile user-agent makes the FS go away.
Google only appears to be asking for feedback about whether the FS is helpful on desktop.