Yandex SERP monitoring tools, and Yandex forums are reporting a potential algorithm update on January 25th.
Some users are reporting seeing fluctuations and changes in traffic/rankings around January 18/19, and then a more substantial change on the 25th – which could elude to some initial pre-rollout testing in some search verticals.
At the time of publishing there has been no official comment from Yandex, or from Plato.
