Common issue
An empty vendor field is easy to miss.
Brand is one of the attributes shoppers search with. When it is blank, the product is harder to match to what someone is looking for.
What to put there
A branded product carries the manufacturer's brand — the brand a shopper would recognise on the packaging, not your shop name.
An own-brand product carries your own brand, because you are the manufacturer as far as the shopper is concerned.
A genuinely unbranded product is the case that needs judgement, and it is the reason our tool treats this check as a suggestion rather than a certain error.