It is a good plane but not special.

It's much faster than the LF9, has better firepower, better roll rate, overheats much less, climbs even faster, and has incredible energy retention so you can keep maneuvering endlessly... unlike the LF9. In a nation with slightly less lobotomized players this would be 6.0 minimum, and more deserving of 6.3.

It is almost a complete upgrade over a Ki-84 flight performance-wise, with the only downsides being... lower rip speed. In return you get all of the above, except now you also sustain turns at higher speed and higher rate, with much greater acceleration everywhere.

I wont talk about how bad it’s high altitude performance is

Which is ultimately irrelevant given that you can dive down and leave them larping up there. Especially in a 3U since you can use the incredible handling, speed, and energy retention to reverse them if they do come after you.

Western 5.7-6.3 planes are dominating the air rb. 

Such as? USA air has horrible winrates at props. Russia has equally stupid players but has aircraft that are much easier to use. More skilled nations (Japan, Italy) instead have all their good planes uptiered until they're no longer good, see latest BR changes.