Legally they can. But we all know that Yandex had always had very strong ties with the Russian government. I used to work for Yandex for more than 6 years in early 2010s and even then there were signs of the state trying to influence it through censoring Yandex.News and various other means. And these days you have to be very naive to assume that it is not controlled by the state and people close to it.