as you can see on my website

As you can see, your .item-col element is inside another .item-col element.

Usually, it's the template templates/content-product.php that display products within loops :

https://github.com/woocommerce/woocommerce/blob/5.6.0/templates/content-product.php

My first guess will be to look at this template if your theme contains it. If not, maybe there is a hook or another template that create this issue...?