I'm glad they've done the work here and put a figure on it - the impact absolutely needed to be quantified - but I also have to say... to the surprise of absolutely no-one with even the most basic grasp of how economies function. People, lots of people, lots of people who have a really deep understanding of national and global economics (unlike me), have been warning about this since talk of tariffs became common cur…
And, if you read the paper, you will find that evidence. How these work depends on initial conditions that vary and exporters will not react in a consistent way.
As a specific example, theoretical research in this area tends to make assumptions around the stationarity of margins that are obviously ludicrous in the context of reality in the US. It is quite easy to justify almost any policy with theoretical research in economics so people who have no understanding of economics will find evidence for whatever position they choose. Reality is quite different.