Fix “Mismatched value [condition]” on Google Merchant Center

Condition mismatches happen when the feed declares one state but the landing page communicates another. Often the site uses "pre-owned" or "reconditioned" while the feed uses "refurbished" — different terms for the same concept that channels can't always map.

The fix can go either direction: align site language to Google's enum (new/refurbished/used), or align feed to site language while keeping Google's enum values. Most teams pick the feed-aligns-to-site approach because changing site language is more disruptive.

For mixed-condition catalogs (some items new, some refurbished), per-variant condition matters. Don't apply one condition across variant groups — each variant might have its own condition.