Add !!membership_level_name!! for PMPro expired email template.

my_pmpro_email_data_membership_level_name.php

<?php
/**
 * Add !!membership_level_name!! to Paid Memberships Pro expired email template.
 *
 * 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.
 * Read this companion article for step-by-step directions on either method.
 * https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */

function my_pmpro_email_data_membership_level_name( $data, $email ) {
	if ( ! isset( $data['membership_level_name'] ) ) {
		$user  = get_user_by( 'email', $data['user_email'] );
		$level = pmpro_getMembershipLevelForUser( $user->ID );

		if ( isset( $level->name ) ) {
			$data['membership_level_name'] = $level->name;
		} else {
			if ( strpos( $email->template, '_expired' ) !== false ) {
				global $wpdb;
				// Get the last level ID with expired status
				$last_expired_level = $wpdb->get_var( $wpdb->prepare( "SELECT membership_id FROM $wpdb->pmpro_memberships_users WHERE user_id = %s AND status = %s ORDER BY id DESC LIMIT 1", $user->ID, 'expired' ) );
				// Get level name and add to email data
				$data['membership_level_name'] = pmpro_getLevel( $last_expired_level )->name;
			} else {
				$data['membership_level_name'] = 'N/A';
			}
		}
	}
	return $data;
}
add_filter( 'pmpro_email_data', 'my_pmpro_email_data_membership_level_name', 10, 2 );