The game isn’t changed. They wouldn’t spend money on a new license for an old slot like that. I really doubt a significant number of slots have had their payout changed, because they are made by some really clever people, wanting to make money. Then they are sent to get verified and licensed by an outside company.
I think a lot of people compare slots to normal games, where the devs can nerf as they see fit. But it’s just bad luck.
Not trying to be rude or anything.