Prices change by date, so maybe that's what happened? The price you see when you look today is today's price. If you choose dates in a high season, the price will undoubtedly be higher. Maybe show us two screenshots, one where we see the listing with the price you like, one where we see the price they give you?
Airbnb should be able to explain it to you. As a host, I just have to say that I don't always see the same thing the guest sees, because Airbnb doesn't show me the service charge or the taxes they charge the guest. We see the service fee Airbnb charges us (that's right, they get you coming and going!), the nightly price, and a cleaning fee. That's it.