Maybe the mortgage rate is a factor but I think FHA loan limits are about 697k, if you had more than 200k down you wouldn’t use fha so that argument doesn’t work. The tax credit is a decent incentive in the lower price range and in other states but on a 900k house it’s like 1%. You can get 2% back using redfin, plus in order to qual for a 900k house your income probably takes you out of eligibility. It’s also not a traditional 1st time buyer price range.
Those are three reasons for the low end rebound, but not really a big factor in that scenario. I’m sure there is an explanation but a loan you can’t use and a credit that is lower than what can be negotiated in comissions aren’t among them.