Indeed, they chose not to attack during that period. But Stalin did pledge to attack within 90 days after VE day. August 8th was the expiration of that 90 day period.
And the Soviets were greatly rewarded for doing pretty much not doing anything in the Pacific theatre. FDR at his advanced age/illness compounded by his leftist politics, should be a lesson for all the stupid people who would vote for Biden. FDR did great damage to the US, and many people died and suffered behind the Iron Curtain.