Welcome to the MongoDB Community Forums @thorin_123 !
If your free cluster has been inactive for more than 60 days it will eventually be paused (related discussion:
Prevent cluster from being disabled due to inactivity period - #2 by Stennie_X).
If that is the case, you can resume your cluster by logging into the Atlas UI. If you cannot remember your Atlas password, you could try resetting via the Forgot Password flow on sign in.
If you no longer have access to the original Atlas account, the most straightforward path would be to create a new free cluster.
If you’d like to understand the difference, please share an example of the two url patterns with any personal details redacted or replaced.
Regards,
Stennie