I recently found out that there are new opening hours for the Star Alliance (SAS) lounge at Helsinki airport. Since the lounge is operated by SAS, the lounge will only be open 1 hour prior to a SAS flight.
If you have a Lufthansa flight and there are no SAS flights at the same time, the lounge will be closed. This happens for example on saturdays when there are lot of Lufthansa flights but no SAS flight.