Ok - so asking this again cuz I didn’t get a response from the previous ask. 
Product photos are square and a good resolution (2100x2100 and 300 dpi which is 7x7 inches. I’ve also tried the 2048 and 1024 recommended by Shopify all with this same result).
On homepage, in the “featured collections” section, images look fine. Click through to a collection and images in the “product grid” section (the name of the block on the page) degrade and are blurry (text on product is particularly blurry).
Actual product images on product page are fine.
I don’t see why this happens or what a fix might be…
Origin theme.