Enable recording consistent 4k24 video in Pro mode all the time. Same deal for 8k24.
(FYI - "Pro" mode and "Pro-grade video" imply professional-level output, which is near-constant. S21 Ultra doesn't do this.)
"Consistent" means 1 of 2 things:
1) Constant 24fps
2) 24fps +/- 1fps
Currently, Mediainfo shows FPS as 1 or 2 or 24+/- [big number]. Makes editing/combining video files difficult to keep sound sync.
Samples from iPhone 12 (4k24):
Fps mode = variable: fps = 24 / min fps = 23.077 / max fps = 24
Fps mode = variable: fps = 24 / min fps = 23.077 / max fps = 25
Fps mode = Constant: fps = 24 (!!!!!)
Samples from S21 Ultra (1st 4k24, 2nd 8k24)
Fps mode = variable: fps = 24 / min fps = 11.992 / max fps = 30.030
Fps mode = variable: fps = 23.976 / min fps = 12.005 / max fps = 30.040
IMHO, one of the few advantages of iPhone is very consistent 24fps, but the video detail is not always the greatest. Implementing consistent 24fps in Android takes away that advantage.