No, they found out after they had arrived in Finland. Not going to explain the format of this tournament, easier to look it up from Wikipedia:
Euro Hockey Tour - Wikipedia
And trust me, the Finnish hockey community is pretty furious about the situation. Liiga and the clubs are not openly criticizing, but they are pretty pissed off. These tournaments are useless anyway, and are only played for money generated by revenue and some TV-deals. And now the Liiga teams pay the price for losing players over these BS games.
For an example, Markus Nurmi (late 2016 Ottawa pick) has been on fire for my team TPS this season. This was his second EHT-tournament of the season. The tournaments alone made him miss some games because Liiga has been forced to play at the same time because of COVID, now the quarantine has made it even more games 13 games in total. In a 60 game regular season, that's almost 25% of games we are missing out on one of our best players for a useless BS tournament.
And many other clubs are obviously pissed of as well. Lundell is the #1 center for HIFK, maybe the best center in the league. And now they lost him for 10 games.