wp-includes/PHPMailer/PHPMailer.php:2103Get an instance to use for SMTP operations.
PHPMailer\PHPMailer\SMTP public function getSMTPInstance() { if (!is_object($this->smtp)) { $this->smtp = new SMTP(); } return $this->smtp; }Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/PHPMailer/PHPMailer.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.