He said “slowing growth rate” not “shrinking economy”. Take 1900 to 2025 (or 2019 if you want to dodge covid) and EMA the (g’-g)/g and it will be visually apparent.

Quite hard to see higher derivatives or rates in the g vs. t graph. You need to plot at least dg/dt vs t to see. But definitely need dg/g vs t to see.

Haven’t looked at the true data (though it would be unsurprising) but your graph on its own hard to spot plus explanation makes no sense.

100,200,300,400,500

100%,50%,33%,25%

Increasing g, decreasing dg/g