It's the official link, and there's no way for it to expire.
Discord is a weird system - we've had some users who could not get in with a link that others have no problems getting in with. If I go into the server and request an invite link, the one above is the only one that comes up. :(
I've had others be able to join if, for example, they try joining on a different device, log in to discord via the browser (instead of the app), etc.
