mypmpro-set-default-level-to-current-level.php

<?php //do not copy

/**
 * This recipe set the default level on the checkout page to the member's current level
 *
 * You can add this recipe to your site by creating a custom plugin
 * or using the Code Snippets plugin available for free in the WordPress repository.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_default_level_from_current_user($default_level) {

    $user_id = get_current_user_id();

    if( ! $user_id ) {
        return $default_level;
    }

    $level = pmpro_getMembershipLevelForUser($user_id);
    
    if ( empty( $level ) ) {
        return $default_level;
    }

    return $level->id;

}
add_filter('pmpro_default_level', 'my_pmpro_default_level_from_current_user', 10, 2);