All productive output doesn't stop during a lockdown. And not all of the world is locked down, including China, the second largest economy in the world.
You are right, we have at least 20-30% productivity in lockdowns. But most large economies are in lockdown and China is just 15-16% of world economy. It is export oriented and only essentials have demand and functional supply chains in these lockdowns. Even with all the best case scenarios, that 3% number does not feel right
