Declared icons
Modern sites commonly publish link rel=icon and related icon declarations in the document head.
Website + SEO
Find the favicon the page publishes.
Read icon declarations from bounded HTML and verify an icon URL returns successfully without rendering or executing remote content.
Result
Diagnostic result
/favicon.ico
Browsers and bots may still request the conventional root favicon.ico when no explicit icon is declared.
Content type
A successful status plus an image/SVG content type is more useful evidence than merely finding an href string.
Stable URL
Favicons are often cached aggressively, so changing a file without changing cache behavior can delay what users and search surfaces see.