I wish DF reached out to GG for some answers, but I don't think they will.
it is simple, their TAA only used 1 previous frame for anti aliasing. normally, other AAA games use all frames rendered in a second to give temporal anti aliasing its juice. this was always known. go check out horizon zero dawn, you will notice its not quite aggresive with its TAA. lots of jaggies and shimmers, but a sharp representation overall.
GG wanted a sharp, clean look on their games, now they've backed out. I'm sure game became noticably blurrier with more frames to feed to TAA.
TAA is practically =
less frames you feed it, more shimmer and sharper, clean image quality
more frames you feed it, minimal shimmer and aliasing, but blurrier, muddy image quality
edit: maybe they also bundled an aggresive sharpening filter. waiting for review vids