The reason you've seen both claimed is that the answer depends on how the payment is structured, and the guidance on this shifted after the August 2024 rule changes rather than settling instantly.
The mechanism works like this. Money a seller pays toward costs that would otherwise be yours is generally an interested party contribution, and each loan program sets a ceiling on those as a percentage of the price, with the ceiling stepping down as the down payment shrinks. Prepaid taxes, points, and title fees typically sit inside that ceiling. If the buyer agent fee is written into the purchase contract as a credit to you, it looks like the same kind of money and is likely to be counted the same way.
A seller paying the buyer's brokerage directly under a separate broker to broker compensation agreement is a different flow, since it never passes through your side of the settlement as a credit to you. Whether a given investor or agency treats that as outside the cap is exactly the point that has been argued over, and individual lenders have taken different positions on it. That's a question for your loan officer, in writing, on the specific program, before the offer goes out.
The practical consequence is worth planning for. If the fee does land inside the cap and you're at a low down payment, you can find that a 2.5% fee has consumed the room you wanted for a buydown, and you discover it in underwriting rather than at offer time. Ask the lender to run the allowance math with the fee included and again with it excluded, so you know both versions before you commit to a number.
