This video from a week ago showed up in my feed yesterday:
Youtube: Builders TERMINATING Buyers Contracts! HORROR Stories in 2021
The tl;dr of it is that builders are finding creative excuses to cancel contracts for lots, and even buildings under construction, in order to turn around and resell them to someone else at an even higher price. Or to find creative ways to get the buyer to pay more if they want to keep their purchase, etc.
Apparently in a market where prices are jumping significantly month to month, the temptation to make even more money by behaving badly is too much to pass up.