I think you might have misread the graphs as they clearly support the title. There are two types

One type (e.g. chart 1 and 4) showing the holdings by governments and central banks, which are clearly falling. The other shows holdings by foreign entities, which is also explained to include many US offshore funds and foreign subsidiaries, so actually still US entities that are holding these treasuries. Here the picture is more amorphous with overall foreign treasury holdings rising in the past years with a dip basically for a number of countries since last year for most countries.

I read it as clearly governments reducing treasuries with investors in some markets still absorbing some.