Windows Spotlight downloads images to a hidden folder structure. The status of the image is managed by the Content Delivery Manager. If the status is corrupted, Spotlight may get stuck on a single image for weeks.
To maintain a "Ready" status without consuming excessive bandwidth, OSs employ aggressive caching. lockscreenimagestatus
When querying this status via the registry or an MDM tool, you will encounter numerical values that indicate the health of the image deployment: Personalization CSP | Microsoft Learn Windows Spotlight downloads images to a hidden folder