It seems that the sizing of the products on the product display page are off. It just seems to have happened out of the blue – although I think it’s important to mention that I have just done some updates.
Thanks for the topic.
WooCommerce developers have added some new options in version 3.3 related to products number per row and per page https://woocommerce.wordpress.com/2017/12/09/wc-3-3-will-look-great-on-all-the-themes/
You need to change number of products per row using Customizer ( > WooCommerce > Product Catalog > Products per row).
WooCommerce set the higher priority for the new option and it overwrites our settings. That’s why we have to remove our option in next update.