wp-includes/SimplePie/src/Enclosure.php:721Get the file size (in MiB)
float|null public function get_size() { $length = $this->get_length(); if ($length !== null) { return round($length / 1048576, 2); } return null; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/SimplePie/src/Enclosure.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.