he’s the private donor. The Flame asked him over email and he admitted it. since The Flame is a reputable newspaper that’s over a hundred years old, I’ll take their word for it.

if it’s a lie and he didn’t admit that, then I’ll gladly admit I was wrong when he files a defamation suit against them.

From the article OP linked to:

Behind the giant donation is Daniel Berntsson, founder and co-owner of the internationally successful IT company Mullvad.

“This is a donation from me personally,” he wrote in an email to Flamman.