This is fairly standard practice amongst the Ryanair, EasyJet, budget type airlines. I use Ryanair to fly to Ireland four or five times a year, and the price goes up the nearer it gets to the date of the flight. I imagine all airlines practice this policy, but I’ve only used budget airlines.
I’m guessing the logic is, if you need to fly somewhere this week, it must be an emergency, so you will pay anything.
Ironically I’ve noted if you hold your nerve, in some cases, if you are booking to fly today, and there’s seats available the price can drop.