Syntax is only the first test
JSON-LD can be syntactically valid while describing the wrong variant or an old price. Start by matching the structured record to the visible item. Check stable identity, name, image and offer details. An empty string is not useful evidence of a property; a property’s presence is not proof of its truth.
Separate a product from its offer
The product describes the item. An offer describes a sale context such as price, currency and availability. A product may have more than one offer. Keep market and seller context in mind instead of flattening every price into one number. Variant relationships deserve separate inspection.
Know what the L0 check establishes
The scanner samples JSON-LD Product objects and reports field presence with a sample denominator. It does not run a complete Schema.org validator, prove Google rich-result eligibility or certify an ACP/UCP implementation. When a page depends on JavaScript, static HTML may not expose the data; that limitation remains visible.