You can disconnect the sync.
In my experience, bad things will happen when you reconnect it.
To avoid bad things you should ensure the same statuses are already setup in the New Campaign.
You can disconnect the Program from Old Campaign and reconnect to new campaign. You may find that the existing Members do not sync with their current statuses until the next change. Thus, you will have to select Program Members and run a flow to update their status in the New Campaign yourself.
You should remove the leads from the SFDC Campaign and delete the Old Campaign once it is working properly.
It is possible Marketo's functionality here has improved and you will experience minimal issues.