https://www.finnair.com/en/info/busi...and-conditions
CHANGES AND CANCELLATIONS
IF YOUR FLIGHT HAS BEEN CANCELLED DUE TO FINNAIR
If your flight is cancelled, Finnair will reroute your flight:
If the rerouted flight is operated by Finnair, you will be rebooked to Business Class based on availability
If the rerouted flight is operated by an airline other than Finnair, you will be rebooked to Economy Class
If there is no Business Class availability due to the rerouting, the following refund policy applies:
Money: full refund of the Business Class upgrade fee
Finnair Plus points and/or upgrade benefits: full refund of points and/or upgrade benefits used for the Business Class upgrade