Russia is buying gold too, it's just to stabilize their currency to make sure it doesn't collapse up against US sanctions. China is doing the same but less because of sanctions, and more because the value of gold is constantly going up which allows them easy profits, but also because if they control a larger share of the gold in the world, they are less susceptible to currency spikes or changes which spurs domestic investment. Gold is a product to buy and sell and profit from. The purchase of it isn't indicative of any major shift in the perception of the economy. Btw the US still holds the largest amount of gold and we have 4 times the amount China does... yet we have a speculative system...
Public debt is an imagined problem. We are VERY far away from not being able to deal with that problem. The major issue is private debt. People's wages have been stagnating while costs have gone up everywhere. If people's basic necessities like rent have all shot up and they don't make more money then it goes on credit card debt. Then a larger and larger share of people's disposable income is going towards credit card payments. Then they cant spend money on stuff which stalls the economy. Like it or not that's the situation. The government has two choices, either force debt forgiveness, or subsidize the hell out of healthcare, education, and social services to eliminate those strains on people's disposable income so they can pay their debts and buy things. This means public debt drives growth because it offsets private debt.