正确的调用应该是:

/wp-json/wc/v3/products?attribute={attribute-taxonomy}&attribute_term={term-id/tag_ID}

在您的情况下，attribute-taxonomy 将是完整的 slug，而 term-id/tag_ID 是Да"的 id.

Where attribute-taxonomy would be full slug in your case "pa_емаг", and term-id/tag_ID the id of "Да".