How? A 65 million unit surplus is more or less in line with other countries: 65/1400 = 5%. At an average family household size of 3, that gives an aggregate household vacancy rate of (up to) 15% (ignoring, of course, that not everyone who owns a home has a family). This also ignores how things like second homes, vacation homes, and excess rural housing stock is counted (given that, y'know, China has had a massive rural-to-urban migration over the past few decades).

The US census reports a vacancy rate of about 10%, and even New York has a vacancy rate of 3%.

Approximately 89.6 percent of the housing units in the United States in the second quarter 2023 were occupied and 10.4 percent were vacant.