Brent nearly down to 4 year lows again but still above the low earlier this year.

It is likely that the Russian bank is already using its gold reserves to prop up the ruble at its current exchange rate in the face of a weakening trade balance and current account. There's a lot of gold to burn so I wouldn't expect any quick sharp devaluations for a while but this is a sign of things to come.
https://www.kommersant.ru/doc/8119223?query=%D0%AD%D0%BA%D1%81%D0%BF%D0%BE%D1%80%D1%82

>inb4 why not just devalue the rubble and let exports go brr
Russia needs imports. They buy ~$250B worth of stuff from China which they can't make at home.