At this point, I don't see why that is any worse than using the services of any US-based Big Tech companies. They have the same kind of anti-privacy business model, their local political regimes have both gone off the rails, and law enforcement and intelligence agencies can legally or extra-judicially snoop through collected data without the user ever knowing.

Some of the services provided by Yandex are, quality-wise, decent enough. I personally tend to find their translation service to be as good or better, as compared to similar services, such as Google Translate or DeepL, so it's usually my API of choice through Mohzi.