“Use it or lose it”-Rule & Strikes: Do I always lose it, when not use it?

Currently many airlines face a lot of problems again: Strikes among Air Traffic Control, public sector, pilots, etc.: Different strike reasons, but same effect: The airlines are forced to do flight cancellations and adjustments. The important question here is: Does a cancellation /adjustment as a result of a strike - no matter what reason – always have the same effect on the grandfather rights?