The US isn't that vulnerable to the high debt-to-GDP ratio since the petrol dollar and dollar as the main currency for world trade, main in foreign reserves of many countries. Same with Japan cause they are the world's biggest creditor, and fund their money to oversea under ADB's loans to developing countries. US and Japan will be fine.
China? Not so much since they have had the real-estate bubble problem for years but never address it. The covid pandemic last year affect the whole world and this somehow take a toll on China's real-estate bubble. Forced their central government to tighten the bank's interest rate for the construction sector,  housing, mortgage,... you name it. Similar to US's montage crisis in 2007-2008.