Hey @Francois_Rulliere, the product feed payload doesn’t include metafields by default, but the webhook subscription input accepts a metafieldNamespaces parameter. I tested setting metafieldNamespaces: ["custom"] on my end and the subscription saved it without error, but I wasn’t able to confirm the payload actually includes them. This thread from another developer suggests they don’t come through.
Still worth trying on your end, but if you need this, I’d plan for requesting read_products from merchants as a fallback.