YCLID tags offer an alternate way of finding the source of a click on an ad. They offer a backup option for those rare cases when the tag in your campaign cannot match a click in Yandex.Direct to a Yandex.Metrica session. YCLID tags likewise help if you didn't enter your Yandex.Metrica tag number when creating a new campaign.
We plan to gradually increase the share of clicks with automatic link tagging. As a result, Yandex.Direct will start using it for all clicks to increase the quality of statistics.
As before, the system will first look at tag data, and will only use the YCLID tag if this field is empty.
You don't need to make any changes to your campaigns — everything will continue to work as it has.
Good luck with your campaigns!