“I represent the younger generation,” Ms. Marin told the Finnish public broadcaster in October, noting, “It feels sometimes that my mere existence is a provocation to some.”
Just a few weeks earlier, the prime minister had taken to her Instagram account, effectively telling the older generation to chill out. “Hey, boom boom boomer, put some ice into your hat, be cooler,” she wrote, quoting a line from a Finnish rap song.
But this time, the reports have not gone away so easily.
After a far-right message board claimed last week that the term “jauhojengi” or “flour gang” — which it interpreted as a reference to cocaine — was shouted in the background of one of the leaked dance videos, the Finnish news media jumped on it. Ms. Marin took a drug test, saying that she had never taken drugs, not even as a teenager.
The test came back negative — but the same day, a photograph surfaced of two women exposing their breasts and kissing in the press room of the prime minister’s official residence during another party, rekindling the outrage.
“What’s next? A porn film?” asked Matti Virtanen, a 59-year-old construction worker waiting for the bus in central Helsinki.
“This gives Finland a bad image — I’m ashamed,” said a 74-year-old grandfather, who identified himself only as Johannes.
In fact, the commentary from abroad has been mostly glowing, if not positively envious of Ms. Marin’s relative youth.
“I know that clip may be extremely confusing to Americans,” the comedian Trevor Noah said about one dance video. “Some countries have leaders who don’t suffer from osteoporosis.”
Bruce J. Oreck, a former bodybuilder who was the American ambassador to Finland from 2009 to 2015 and still spends part of the year in the country, said that the United States should take note.
“This is so generational,” Mr. Oreck, 69, said. “There is an incredible reticence of the older generation to pass on the torch,” he added, noting, “No decision that any of these knuckleheads in Congress are making today will impact them. They’re not going to live through the climate crisis.”
“The purpose of an institution is to serve the current and future population, not to preserve the institution itself,” he said.
Yasmine M’Barek, writing in the German weekly Die Zeit, summed it up this way: “Sanna Marin is the prototype of a successful millennial in politics. Live with it!”
That sentiment was widely shared among young Finns emerging from a row of wooden cabins at a public sauna in Helsinki one recent afternoon to immerse themselves in the Baltic Sea.
“It’s inspirational!” beamed Miisa Myllymäki, a 23-year-old bartender whose friend recently served the prime minister at Flow, one of Finland’s biggest music festivals. “She shows that you can be young and human and still do politics in Finland, and that’s good because sometimes it can feel like politics is just for older people.”
At Siltanen, a music venue in central Helsinki, Johanna Helle, a.k.a. D.J. Uha, was on the decks. “The media are targeting the prime minister all the time — she’s female and young,” Ms. Helle said, calling the episode “click bait.”
Niko Vilhelm, one of the lead singers of Blind Channel, a professed “violent pop” group that represented Finland in the Eurovision song contest last year, said that he had been on a tour bus when his phone lit up with alerts and social media memes about the prime minister’s partying.
“The headlines went crazy. I’ve never seen anything like it. And it hasn’t stopped,” Mr. Vilhelm said. “The media needs to chill out.”