I am pretty sure that the pandemic has something to do with it this year. From memory (and I could be wrong), the ticket prices went up dramatically around 2012 / 2013... there hasn't been a slump in demand so I think they have shown over the last 7 or 8 years that Origin is worth that price tag and that interest for tickets haven't wained because of the price. It is the NRL's job to use their assets to maximise revenue for the good of the game.
It's just how economics works - at the $50 average price point there might be 200,000 willing and able to pay that for State of Origin tickets. At the $100 average price point that number night decrease to 150,000 people willing and able to pay to attend. At the $300 average price point, there might be 60,000 willing and able to pay. Until you hit the point where less than 50,000 are willing and able to pay to attend Origin at Suncorp then the price won't drop.
Obviously all the numbers in the above scenario are hypothetical because I don't have the data but it's how the principle works.