Hello, planitrph!
From what I see, Your product images are in very small resolution (300×300 px). since you have the product in your webshop in two columns, the container in which the images are located is almost twice the size of the image and when the image is expanded to fill the container, the quality is lost. To fix this, you need to add higher resolution images or try displaying products in 3(or 4) columns instead of two.
Customizing ▸ WooCommerce ▸ General… Shop columns
https://prnt.sc/qa7ndc
Regards