tml_ms_get_user_signup_form()

function tml_ms_get_user_signup_form( $user_name = '', $user_email = '', $errors = '' ) {
    if ( ! is_wp_error( $errors ) ) {
        $errors = new WP_Error();
    }

    // phpcs:disable WordPress.Security.NonceVerification.Missing -- read-only: mirrors the field's pre-filled default, not processed/acted on.
    $signup_for = isset( $_POST['signup_for'] ) ? esc_html( $_POST['signup_for'] ) : 'blog';
    // phpcs:enable WordPress.Security.NonceVerification.Missing

    /** This filter is documented in wp-signup.php */
    $filtered_results = apply_filters( 'signup_user_init', compact( 'user_name', 'user_email', 'errors' ) );
    $user_name        = $filtered_results['user_name'];
    $user_email       = $filtered_results['user_email'];
    $errors           = $filtered_results['errors'];

    $form = tml_get_form( 'user_signup' );

    $fields = compact( 'user_name', 'user_email' );
    foreach ( $fields as $field => $value ) {
        $field = $form->get_field( $field );
        if ( ! $field ) {
            continue;
        }

        $error = $errors->get_error_message( $field->get_name() );
        if ( $error ) {
            $field->set_error( $error );
        } elseif ( null !== $value ) {
                $field->set_value( $value );
        }
    }

    return $form->render(
        array(
            'before' => '<h2>' . sprintf(
                __( 'Get your own %s account in seconds' ), // phpcs:ignore WordPress.WP.I18n.MissingArgDomain, WordPress.WP.I18n.MissingTranslatorsComment -- reusing WP core's translated "Get your own %s account in seconds" string (see wp-signup.php), not a TML-specific string; no translators comment since it never enters TML's own .pot.
                get_network()->site_name
            ) . '</h2>',
        )
    );
}

View src/includes/ms-functions.php, line 961 on GitHub