We track task card clicks on the server side and assign the newcomer task edit tag when the user edits those articles. This tracking is supposed to last 7 days but we are relying on cache invalidation and are caching the list of tracked articles as a single entry, and merge new page IDs into it as needed. So the expiry happens for the whole list (when the user doesn't click any task cards for a week), not per-article (seven days after the user clicked that specific task card).
The result is that we add the change tag to any edit where the user has clicked on the relevant task card some time in the past, no matter how long ago it happened, as long as the user is regularly interacting with task cards in general.