Part of the reason the bond markets started freaking out yesterday is that everyone finally woke up and realized that everything they thought still existed to constrain Trump's worst impulses (regarding international trade) has failed. Congress refuses to assert its power, the courts are too slow to get in his way, and until his 180 yesterday it sure as hell looked like nobody in the business world had the ability to change his mind.
American treasury bonds have been perceived as the safest investment in the world for a hundred years because everyone believed they were backed by the full faith and credit of the United States. Even through the S&L crisis, the dotcom bubble burst, the great recession, and the covid recession the world still thought that our debt was far and away the safest, because it was backed by the strongest economy on earth, protected by the largest military on earth, and guaranteed by a state composed of institutions that fully understood how important and how powerful the full faith and credit of the United States of America is. Even after we elected Trump once, enough guardrails held that the world still generally believed that.
Now everyone realizes what a huge fucking mistake that was and our credit has been substantially diminished (at the very least) forever.