Here's a Sixth Tone article about it from last month. The long short of it is that it's common practice in China to buy a house before it gets built, and there are industry regulations requiring that money spent on unbuilt houses goes into protected accounts to protect the buyer, but it seems that a lot of developers may have been investing the money illegally and when the stock market dipped during COVID a lot of it vanished. We're hearing about it now because a lot of homes are supposed to have been finished by now that aren't even started, and the development companies are complaining about not having the cash to do it.

Regardless of what the central government does or doesn't do, a lot of working class Chinese people are currently holding the bag, and so there are mortgage strikes and protests breaking out. The stuff about tanks is completely made up though - AFAIK there were images from an unrelated military parade/exercise that went around Twitter with people saying it was a government crackdown on protesters.