Hi, both of dear friends above
As my understand, have you reset the image size in woocommerce setting? Just change the image size to double size.
I have mentioned in the documentation as below
Please note, if you actived WooCommerce plugin, you should also change the default image size in “Woocommerce > setting > catalog > image options”, just change all default size to double size, for example, change 150px to 300px.
Thanks