What does it mean for a market to have inefficiencies?
Regular person could absolutely see it and be prepared. Even today market still doesn’t price in Italy-style or China-style lockdowns.
It does not change the fact that the market had an inefficiency in pricing this information into many assets two weeks ago.
If someone bought or sold assets based on a strategy based on this belief (and certainly at least some people did), then they exploited that perceived inefficiency correctly without hindsight.
In an ideal world, markets should be perfectly efficient (near immediate) at exposing things which are misvalued because people can make money if they understand some fact that the market doesn't and then that fact will be accounted for.
In reality they just converge on the average of beliefs weighted by how confident a given actor is for a given belief and how much money they have to put behind the belief, and people are extremely imperfect, especially when it comes to predicting the outcomes of complex systems. Given this, there exist all sorts off "inefficiencies", or times when the current state of the market fails to accurately account for some underlying reality which leaves an exploitable opportunity to buy or sell a mispriced asset.