What is happening when "Fetching Metadata" after swipe-down action in a library on iOS?

On iOS, when inside of a library, like “All Movies,” you can swipe down on the listing and you’ll see a spinner with “Fetching Metadata” text. Considering every item in this library already has metadata, what is actually happening when this is done?

Does it refresh all the existing metadata, as though I manually edited metadata to re-select the same movie title so the metadata like poster gets updated, or something else? What’s happening?

This is the equivalent of tapping the Scan For Changes option in Infuse > Settings > Library.

This was added back before the Library option was available, so its kind of a legacy feature.

Ahh okay–thanks for the info.