A renegotiated commission tells you who blinked first.

Commission is agreed in the mandate before a house is listed, so a request to cut it once an offer is on the table is less about money than about who bends under pressure. The timing is rarely an accident. A buyer has signed at a price a little below the seller's hope, the agent is close to a sale after weeks of work, and the seller says the deal only works if the commission comes down.

A yes feels like protecting the sale. But the seller learns from it, and so does everyone the seller talks to. The agreed rate becomes an opening position, and next time the request comes earlier and asks for more. An agent who bends every time ends up negotiating commission on every deal instead of selling houses, while the work that justified the rate gets squeezed to fit the smaller number.

Commission can be negotiated, and the natural moment is when the mandate is signed, with both sides clear about what the work includes. A late change is a different thing, because it arrives after one party has already done most of the work and has the least room to refuse.