It's a real rule, not one agent being pushy. Under the National Association of Realtors settlement that took effect on August 17, 2024, an agent working with you as a buyer has to have a written representation agreement in place before touring a home with you, and that agreement has to state how the agent gets paid. Your brother's 2019 experience was the old world, where the fee was published on the Multiple Listing Service (the shared database of listings) and buyers often signed nothing.
A buyer representation agreement is a contract between you and the agent's brokerage. It says the agent works for you, and it says what the agent's fee is. Historically that fee came out of the seller's proceeds, and in most markets sellers still cover it, because a listing that offers nothing to the buyer's side gets fewer showings. What changed is that the amount is no longer advertised in the database, so it gets asked about deal by deal.
On being stuck: that depends entirely on what you sign. These agreements have a length, and some run six or twelve months and cover an entire area. You can ask for a shorter one. Some agents will write it for a single property or for thirty days, which is a normal thing to request if you're still deciding whether this person is right for you.
Also worth knowing before you sign anything: the open house agent represents the seller at that house. She can show you the door and hand you a flyer without any agreement, because she's there for the seller.
