Yandex is one of Kagi's index sources. They used to publish a list of their sources but have changed it to a generic "we use multiple sources" because they got so much shit for using Brave (because of its founder’s bigotry) and Yandex (because of the ethical dilemma of paying a company headquartered in Russia which in the best case pays taxes and in the worst case has Kremlin/military involvement). This has been a contention debate for awoke, you can search their forum and discord for more details.