The mitigation wasn't on a small scale. People globally were in lockdown. That's a massive scale reduction in polluting activities. And, as you pointed out, it worked. But, it was in place for too short a time to have any real impact and was not a sustainable solution. However, I think it did show the world that we humans are inarguably the cause of climate crisis. I think it also showed the world that we humans can do something about it – if only we can find the will to create and stick to sustainable solutions.