wp-includes/formatting.php:2866Navigates through an array, object, or scalar, and encodes the values to be used in a URL.
$valuemixedmixedfunction urlencode_deep( $value ) { return map_deep( $value, 'urlencode' );}Introduced in 2.2.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/formatting.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.