To state a bit more simply: the rate at which this spending has gone from about 0% to 1.2% is extremely fast which is point the author is trying to make.

The Q1 GDP comment is stunning because what it says is that if the same Q1 had happened just two years ago there’s a very good chance we’d be looking at a modestly sized recession. Now of course things aren’t zero-sum and it’s impossible to really make a useful claim like that but it’s still striking.