Missing field "review", No global identifier provided (e.g., gtin, mpn, isbn), Missing field "aggregateRating"I searched the internet, some blog says it is Structured Data issues.Does anyone know how to fix it?
Don't sweat it. Unless both your theme has these, and you've populated them for all your products, it's just that - a warning. Nothing bad will happen, and these are not required bits of meta data.
My theme doesn't have those. They affect all my products' organic search. My merchant center shows "Limited performance due to missing identifiers" for all the products.