Do I need to warn the user about the use of analytics systems on the site?

Question

Law in IT

Let's say that the site uses Yandex.Metrica or Google Analytics. Should the user be warned about this? If so, is there anything else needed besides the warning itself?

Answer 1

It is mandatory for the user to consent to the use of personal data.
If such data is not included in the analytics, then the notification can be omitted.

Answer 2

I have never seen such a warning.