In 2015, foreigns stopped buying US treasuries essentially they decided to stop funding growing US deficits. Which means the US is on the hook for any new government spending that occurs since there is no, or very little, lending coming into the US from global central banks.
We then had to source it ourselves.
This began with structural changes money market funds and bank capital requirements. (Basil 3 and Dodd Frank)
This forced institutions to buy treasuries for their balance sheets
These money market funds doubled from 0.8trillion to 2.1trillion from 2014-2016 and then 4.9trillion by 2020.
These MMFs almost exclusively bought short term maturity t-bills, essentially becoming a large new lender for the government.
However these institutions only have so much money so it could only buy a limited amount of time.
Beginning on March 2020, the government began massive fiscal expenditures to deal with the fallout of Covid.
This time was different, since global banks weren't lending to the US, our government had to print the difference.
The FED had to step in and back stop the Treasury US fiscal deficits which hadn't mattered in 40 years, now began to matter.
The FED directly purchasing treasuries is harmful to the system and is directly inflationary to the United States instead of allowing other global central banks to print and inflate their own currencies.
That's not how a global reserve currency is supposed to work.
That is like a chef eating her own cooking more than her customers do.
In ONE YEAR the FED went from owning half as much treasuries as foreign central banks to more than ALL OF THEM COMBINED.
In 2008 when the FED did this the money had stayed in the banking system due to the nature of QE, however this time it was the government and entire US economy that needed to be bailed out, so that is where the dollars had to flow. This led to a massive influx of dollars into the real economy and thus the recipe for a large surge in inflation in the coming years.
With fiscal deficits at 2.8trillion in 2021 and foreign central banks financing almost none of it, that means there is 2.4trillion in US treasuries that need to be bought.
There is no surprise that foreign leaders have seen those writing on the wall and have begun to pull support for US treasuries.
Would you want your hard earned taxes being invested in a reserve asset that's losing 7.5% of its value annually and is projected to lose even more as the debt payments come due?