https://musicbrainz.org/relationship/b35f7822-bf3c-4148-b306-fb723c63ee8b

Most labels have a singular logo used for specific periods of time.  The start and end dates on the Label-URL relationship are commonly used to indicate when the logo was used by the label, which userscripts can render as shown in the attached screenshot.

It's not meaningful for these URL dates to indicate the upload timestamp of the image metadata or an unknown deletion timestamp of the image URL.