Hello @irbis16,
Good Day!!
Thanks for your patience!!
We’ve tested your given URL and noticed on your side that there is a JS error occurring from ROISTAT (not sure if it is the plugin)-as the phone field may break if there is a JS error.
We suggest you clear that JS error, or deactivate all other plugins except our plugins “Back In Stock Notifier for WooCommerce” and “WooCommerce” (temporarily) to see if the error persists. Sometimes the issue may arise due to conflict between different plugins.
Here we have attached the screenshot of the JS error on your end.
https://drive.google.com/file/d/1W-VfJmU0Ba-Mr6utuzC0QDBiJOeAX2-T/view?usp=sharing
Let us know.
Thanks.