Ok, my bad, this seems to be a problem of Woocommerce as well, since by default it has values it does not respect, my thumbnails for producst and single products were about 200×200 and 485×485, even though, in the settings page woocommerce shows 90×90 for both, when I used this tool it obviously respected those values which I did not check before doing it, I replaced them with the values the page actually showed and keeps showing me, the tool changes the image to a 90×90 image, but it kept showing at 200×200 hence the reduction in quality, I did not noticed this at first, because woocomerce CSS keeps this images at 100% width, strecthing them, I apologize for the previous post and thanks again
