If you enter Russia under a visa-free regime, your total stay is generally limited to 90 days during each calendar year. The counting period runs from January 1 through December 31 and resets at the beginning of each new calendar year. Specific bilateral agreements or other legal grounds may provide different stay periods.
https://london.mid.ru/en/press-centre/on_changes_in_the_period_of_stay_of_foreign_citizens_arriving_in_the_russian_federation_on_a_visa_fr/