This seems to happen only every two products, is that right? It looks like the problem is in the Theme’s media queries.

To fix it, go to Dashboard > Appearance > Customize > Additional CSS and add the following code in the box:

@media only screen and (max-width: 768px) {
   .woocommerce ul.products[class*=columns-] li.product, 
   .woocommerce-page ul.products[class*=columns-] li.product {
      width:100%;
   }
}

Remember to click the Publish button before exiting the screen.

Hope it helps.

What do you mean by weird? Can you give more detail of what it looks like and what should it look like instead?

Thanks.