Hello, I am a complete noob when it comes to mortgages and the like so please don't bludgeon me for my ignorance. Sorry if I say anything silly.

So I got preapproval for a mortgage from Rocket Mortgage, right? Next I ask the loan officer what my interest rate, monthly payment, down payment, and closing costs will be. His exact words were "We will discuss your loan options after you have accepted a deal. The interest rate is a floating interest rate from 5 to 7%."

What is stopping Rocket Mortgage from absolutely screwing me and giving me the highest interest rate after I have accepted a deal and have made a good faith deposit into escrow and cannot legally back out of the deal? I feel like they are trying to scam me.

Also, I find Rocket's business practice extremely strange because I've gotten preapprovals from other places like Guild mortgage and Veterans United, and they would give me a document with an entire breakdown of what my interest rate, monthly payments, and approximate cash to close will be.