PHP Fatal error: Uncaught TypeError: Unsupported operand types: string * string

Hi,
I got this:

[29-Mar-2022 08:52:37 UTC] PHP Fatal error:  Uncaught TypeError: Unsupported operand types: string * string in /wp-content/plugins/woocommerce/includes/class-wc-cart.php:2032
Stack trace:
#0 /wp-content/plugins/yith-woocommerce-request-a-quote/templates/emails/request-quote.php(59): WC_Cart->get_product_subtotal()
#1 /wp-content/plugins/woocommerce/includes/wc-core-functions.php(345): include('...')
#2 /wp-content/plugins/yith-woocommerce-request-a-quote/includes/emails/class.yith-ywraq-send-email-request-quote.php(130): wc_get_template()
#3 /wp-content/plugins/woocommerce/includes/emails/class-wc-email.php(541): YITH_YWRAQ_Send_Email_Request_Quote->get_content_html()
#4 /wp-content/plugins/yith-woocommerce-request-a-quote/includes/emails/class.yith-ywraq-send-email-request-quote.php(81): WC_Email->get_content()
#5 /wp-includes/class-wp-hook.php(307): YITH_YWRAQ_Send_Email_Request_Quote->trigger()
#6 /wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()
#7 /wp-includes/plugin.php(522): WP_Hook->do_action()
#8 /wp-content/plugins/woocommerce/includes/class-wc-emails.php(170): do_action_ref_array()
#9 /wp-includes/class-wp-hook.php(307): WC_Emails::send_transactional_email()
#10 /wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()
#11 /wp-includes/plugin.php(474): WP_Hook->do_action()
#12 /wp-content/plugins/yith-woocommerce-request-a-quote/includes/class.yith-request-quote.php(598): do_action()
#13 /wp-includes/class-wp-hook.php(307): YITH_Request_Quote->send_message()
#14 /wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters()
#15 /wp-includes/plugin.php(474): WP_Hook->do_action()
#16 /wp-settings.php(587): do_action()
#17 /wp-config.php(109): require_once('...')
#18 /wp-load.php(50): require_once('...')
#19 /wp-blog-header.php(13): require_once('...')
#20 /index.php(17): require('...')
#21 {main}
  thrown in /wp-content/plugins/woocommerce/includes/class-wc-cart.php on line 2032

What to do?