woocommerce Images are blurry.

hi, I create a woocommerce site (www.funkyshit.gr) for a friend and most of my images in products are blurry. I use a plugin “YITH WooCommerce Zoom Magnifier” so that they can zoom in the images, if go to a blurry image and zoom you can see the image very clear, so I dont think there is a problem with the image. also some product images look fine with or without zoom like this one.

but most of my item show like this

any ideas why is that happening?