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L2 loops often create such busy links (from the looping traffic), effectively your network becomes unusable.

Generally all network services dealing with a L2 loop become unusable.

Generally ports do not enter a special state once a loop forms.  (However, depending on device features L2 loops might be prevented by the device detecting the possible forming of a L2 loop and perhaps error disabling the port.  [E.g. BPDUGuard])

You fix it by breaking the loop.  Might be accomplished by shutting ports, if you can still manage the devices, or by physically disconnecting links.