Why did the property consultant buy a new house and sign a formal purchase contract and leave?

If it is unreasonable, both parties of any bilateral contract shall hold one copy.

I suggest you communicate with the property consultant to clarify the reasons for withdrawing the contract and when to withdraw it.

Because some developers require buyers to sign contracts first, then stamp them uniformly, and finally return one of the contracts to buyers.

If so, there is no need to worry too much. After the contract is returned, you can see if the key terms have changed. In fact, it is very unlikely that developers will cheat property buyers in this way.

If the reply will not return the contract to the buyer, then you must insist that the other party return it.

If the other party insists on not returning, it can report to the housing management department.