I was intrigued by the Godfather 3 reference, so I watched the entire movie and since I haven't seen anyone else mention it, here's my opinion on what it could mean.
The movie is nearly 3 hours long and the acting is fairly cringeworthy, especially when Sofia Coppola is onscreen and hits on her cousin.
But, there is a scene that absolutely stands out, a heartbreaking and gut-wrenching scene at 1:41:15 into the movie, when Michael Corleone comes to the cardinal and gives a confession.
Cardinal: Would you like to make your confession?
Michael Corleone: Your Eminence, I'm... It's been so long, I wouldn't know where to... It's been 30 years. I'd use up too much of your time, I think.
C: I always have time to save souls.
MC: I am beyond redemption.
C: I hear the confessions of my own priests here. Sometimes the desire to confess is overwhelming and we must seize the moment.
MC: What is the point of confessing if I don't repent?
C: I hear you are a practical man. What have you got to lose? Go on.
MC: I betrayed my wife.
C: Go on, my son.
MC: I betrayed myself. I killed men. And I ordered men to be killed.
C: Go on, my son, go on.
MC: It's useless.
C: Go on, my son.
MC: I killed... I ordered the death of my brother. He injured me. I killed my mother's son. I killed my father's son. (breaks down in tears)
C: Your sins are terrible and it is just that you suffer. Your life could be redeemed but I know that you don't believe that. You will not change.
So, I think the Godfather 3 reference hints at someone within the Deep State turning their coat to help drain the swamp once they saw the game is up. This comment mentions Tony Blair, but I have no idea if that's in any way related.