I don't know when changes were made or what those changes were. I do know that until around 2005, every time I went into a Novus Ordo confessional--and chose the "behind the curtain option--I started out with, "Bless me, father, for I have sinned." And went on from there as I was taught to do in second grade in the mid-1960s. No priest ever said anything, and it I thought nothing had changed.
The very last time I went to a Novus Ordo confession was at the parish that had the approved Traditional Mass. The priest in the confessional was not the "TLM priest", but the pastor, an old Monsignor. I went in and knelt before the curtain and before I had a chance to say anything, the priest started reading out loud. It took me a while to realize he was reading a passage from scripture. I was so flummoxed I wasn't sure what to do and pretty much forgot everything I was going to say. When the priest told me to tell him my sins, I managed to say something and was told that probably wasn't really a sin. Then he talked a while and gave me penance--a couple of Hail Marys--and told me to express my sorrow using my own words. I said an Act of Contrition. He sighed, and, I think, said words of absolution. By then I really wasn't paying attention.
When I got home, I started searching on the internet and found articles about the New Rite of Reconciliation. Until then, I had thought the only thing they did was introduce an optional face-to-face confession. It turned out that he was the first priest I ever went to that made sure that everyone went through the New Rite and that, for years, every priest I had gone to just went with whatever the penitent did. At least, in my case, they did.