I think that nested anchors in the product list are illegal (Add to Cart button nested inside anchor for the product):
See 12.2.2 here: W3
No, the product list does not contain nested anchor links. It have a single anchor link wrapping the content inside the <a> tags. The inner <a> element with the class “ref-button preview-toggle” is a child element of the <div> element with the class “ref-addons” not a nested anchor link.