This response completely fails to address what is the issue for me and many others, and frankly I find it quite offensive. The Örebro Party uses racist and transphobic rhetoric and dog whistles, and openly advocates for ethnic cleansing. Their political actions have already hurt people I care about. Berntsson's donation is explicitly meant to support the party in bringing their politics to the national level. This would bring material harm to me, to family and friends, and to many others.
And Berntsson's ability to fund ÖP in doing that harm is directly linked to the financial success of Mullvad. Whether you or Mullvad agrees or disagrees with Berntsson or ÖP is irrelevant. Thanks to Berntsson, more money to Mullvad means more harm to us. So why on Earth would I pay you anything?! On the contrary, it would quite obviously be in our best interests if Mullvad fails as a company, if possible to such an extent that Berntsson is ruined financially and can no longer fund "nationalist socialist" parties such as ÖP.
It just doesn't matter whether Mullvad believes in free speech or not, not when Berntsson is making it so that giving you money causes us to be persecuted and harmed. And to be perfectly honest, I find your framing of this as "philosophical" to be profoundly appalling, and it tells me that you do not at all understand what is actually going on.