wpum_add_account_tab.php

<?php

/**
 * Register a new tab within the account page.
 *
 * @param array $tabs
 *
 * @return array
 */
function my_wpum_register_new_account_tabs( $tabs ) {

	$tabs['custom-slug'] = [
		'name'     => esc_html__( 'Custom Title' ),
		'priority' => 3, // Change this to define the position in the menu
	];

	return $tabs;

}
add_filter( 'wpum_get_account_page_tabs', 'my_wpum_register_new_account_tabs' );