Why does FSR FG in Cyberpunk suck?

I can't help but be very disappointed by CDPR's implementation of FSR Frame Generation in Cyberpunk 2077. I understand being a heavily sponsored Nvidia title and not having FSR 4 right out the gate. I installed OptiScaler and injected FSR 4 into it and it looks great! No matter what I try, however, I can't get past how poorly CDPR's implementation of FSR FG is in the game. Motion feels very "juddery" as if I was seeing duplicates of the same frame sometimes. It's unexplainable how bad it is compared to DLSS FG where the experience felt miles smoother. This is not an issue in the other games I have tested FSR FG on. The Last of Us Part 1 and Warhammer 40k: Space Marine 2 run great with FSR 4 and Frame Gen, and even in Black Myth Wukong with the injected FSR 4+FG runs great as well. Has anyone else shared this same sentiment? I'd like to know.

With all that being said, as a former Nvidia GPU user and now returning AMD GPU user, I've gotta say I'm pretty impressed with the suite of features AMD implemented into the new 9000 series of cards that bring it up to par with the Nvidia competition. I used a lot of DLSS features when I was using my Nvidia cards and was pleasantly surprised by the quality of FSR 4 and FSR Frame Generation. They're genuinely transformative and FSR 4 is a big milestone since its previous versions of FSR were very subpar. The RX 580 was the first GPU I ever had in my first build and it's been sick seeing AMD's GPUs compete this well with Nvidia's (assuming that you can find them at a fair price).