Yandex isn't just a "Russian language search engine", it's a Russian company with quite close ties to the Kremlin. See: https://www.zois-berlin.de/en/publications/zois-spotlight/th...

I'm frankly a bit surprised that it's even legal for a US company like Kagi to do business with Yandex, considering it's sanctioned: https://sanctionssearch.ofac.treas.gov/Details.aspx?id=18711. Though in fairness, I don't know enough about how exactly sanction laws work so it might be legally okay even if I find it morally questionable.