Try to change the class contact-form in the HTML.
FROM:
<form class="contact-form custom-form-style-1" action="php/contact-form-recaptcha-v3.php" method="POST">
TO:
<form class="contact-form-recaptcha-v3 custom-form-style-1" action="php/contact-form-recaptcha-v3.php" method="POST">
