What does "limited as it is" mean?
Solution 1:
A parenthetical phrase of the form adjective as it is mainly means that the subject is adjective, but is often used to minimize the impact that it has on whatever is being discussed.
So the statement is saying that there was a limited (small) shift away from China that began before the trade war, but it hasn't prevented China from having one of the fastest growing economies in the world.
Another example of this would be
As strong as he is, he still can't lift 1000 pounds.