Filter [`wp_nav_menu_objects`](https://developer.wordpress.org/reference/hooks/wp_nav_menu_objects/). It will contain the sorted list of nav menu items to render. Have a look at [`wp_setup_nav_menu_item`](https://github.com/WordPress/WordPress/blob/eb7df1379be5f7b24a6d29c1a390c1b1bf2e6183/wp-includes/nav-menu.php#L732) for some properties you can use.

Here's a quick (untested) example.

    add_filter( 'wp_nav_menu_objects', function( array $items, object $args ) {
    
        if ( 'someThemeLocation' !== $args->theme_location ) {
            return $items;
        }
    
        return array_filter( $items, function( $item ) {
            return '/user-specific-thingy' === $item->url 
                && ! is_user_logged_in();
        } );
    
    }, 10, 2 );