wp-includes/SimplePie/src/SimplePie.php:3279Get the favicon for the current feed
string|bool public function get_favicon() { trigger_error('Favicon handling has been removed since SimplePie 1.3, please use your own handling', \E_USER_DEPRECATED); if (($url = $this->get_link()) !== null) { return 'https://www.google.com/s2/favicons?domain=' . urlencode($url); } return false; }One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
none to string|bool.verified against sourcesrc/wp-includes/SimplePie/src/SimplePie.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.