wp_replace_insecure_home_url( string $content )

Source

File: wp-includes/https-migration.php

function wp_replace_insecure_home_url( $content ) {
	if ( ! wp_should_replace_insecure_home_url() ) {
		return $content;
	}

	$https_url = home_url( '', 'https' );
	$http_url  = str_replace( 'https://', 'http://', $https_url );

	// Also replace potentially escaped URL.
	$escaped_https_url = str_replace( '/', '\/', $https_url );
	$escaped_http_url  = str_replace( '/', '\/', $http_url );

	return str_replace(
		array(
			$http_url,
			$escaped_http_url,
		),
		array(
			$https_url,
			$escaped_https_url,
		),
		$content
	);
}