Custom cart notice based on user total purchased amount in Woocommerce

Try the following instead (I have revisited a bit get_customer_total_purchases_sum() function):

// Utililty function to get customer's total purchases sumfunction get_customer_total_purchases_sum() {    $current_user_id = get_current_user_id(); // Current user ID    if( $current_user_id == 0 ) return 0; // we return zero if customer is not logged in    global $wpdb;    // return the SQL query (paid orders sum)    return $wpdb->get_var("SELECT SUM(pm.meta_value) FROM {$wpdb->prefix}postmeta as pm    INNER JOIN {$wpdb->prefix}postmeta as pm2 ON pm.post_id = pm2.post_id    INNER JOIN {$wpdb->prefix}posts as p ON pm.post_id = p.ID    WHERE p.post_status LIKE 'wc-completed' AND p.post_type LIKE 'shop_order'    AND pm.meta_key LIKE '_order_total' AND pm2.meta_key LIKE '_customer_user'    AND pm2.meta_value LIKE '$current_user_id'");}// Display a custom noticeadd_action( 'template_redirect', 'total_purchase_custom_notification' );function total_purchase_custom_notification( ) {    if ( is_wc_endpoint_url('order-received') && WC()->session->get( 'purchases_sum' ) ) {        // We remove this session variable in thankyou page (if it still exist)        WC()->session->__unset( 'purchases_sum' );    }    // On cart page we display a custom notice    elseif( is_cart() ) {        // Get customer's purchases total sum and set it in WC_Session        if( ! WC()->session->get( 'purchases_sum' ) ){            WC()->session->set('purchases_sum', get_customer_total_purchases_sum());        }        $total_purchases  = WC()->session->get( 'purchases_sum' );        if ( $total_purchases == 0 ) return; // We exit (no purchases or non logged users)        if ( ( 10000 - $total_purchases ) > 0 )        {            wc_add_notice( sprintf(                '<a class="button alt wc-forward" style="float:right" href="%s">%s</a> ' .                __( "You need an extra %s at all to get a...", "woocommerce" ),                get_permalink( wc_get_page_id( 'shop' ) ),                __( "Continue shopping", "woocommerce" ),                strip_tags( wc_price( 10000 - $total_purchases ) )            ), 'notice');        }        else        {            wc_add_notice( __( "......", "woocommerce"), 'notice' );        }    }}

This code goes on function.php file of your active child theme (or theme). Tested and works.