@kelly-sensei Just to clarify ... is this pop out suggesting you make Yandex the default search engine? I presume you live in an area where that is even possible - in this country Yandex is not among the built-in searches and so couldn't be set as default.
(The alternative, by the way ... I know for a while there Microsoft resorted to pop-ups suggesting Edge as default browser, so it isn't impossible that some software on your system would suggest the Yandex browser as default browser.)