The rule for tips in Russian restaurants is very simple.
If yoo like the food and service, put 10% of the bill in cash — on the table or in the bill cover.
7-8% are ok too.
Подписывайтесь на телеграм-канал Вкладер и потом не говорите, что вас не предупреждали: https://t.me/vklader.
If you don’t like the restaurant, leave nothing.