People dont just randomly decide to pack equipment suited to cutting metal cables and go collapsing signal towers. Calling it "vandalism" is belittling the severity, though maybe they just dont want people to panic.
Its also worth noting there has been multiple breaches at water infrastucture facilities around finland. Its likely that russia is testing its ability to sabotage infrastructure, but that is hard to prove unless they get caught or submit written confession. Considering how everything else is run here that involves important people doing important decisions, i'm a bit worried.