How to change image size in category block

The product category block is great, but the product images by default appear TINY (150 pixels) and the block has no option for changing the size. I’m guessing from the css class size-woocommerce_thumbnail that it’s set to use a size called woocommerce_thumbnail, so I tried redefining this size to 300 pixels and regenerating thumbnails. But the problem remains the same and the image element has the following sizes attribute set: sizes="(max-width: 150px) 100vw, 150px" which means the image remains blurry. Is there any way around this? 150 pixels is really tiny.

This is how I redefined the size, perhaps I missed something here.

function redefine_woocommerce_thumbnail_size() {
add_image_size( 'woocommerce_thumbnail', 300, 300, true );
}
add_action( 'after_setup_theme', 'redefine_woocommerce_thumbnail_size' );