Question about average rank and FFR rank

[Dorby]

So, I've been playing a little bit here and there over the last few months, updating my scores a bit and trying to catch up on the hundreds of songs I haven't ever ranked on.
However, I have noticed that while my grandtotal rank keeps going down, my FFR rank and average rank keep going up?

Example :

As of 9/6/21

FFR Rank : 963
Average Rank : 2,804
Grandtotal Rank : 1,068
Grandtotal : 7,092,614,785

compared to 12/9/2021

FFR Rank : 989
Average Rank : 4,407
Grandtotal Rank : 1,021
Grandtotal : 7,394,867,800

Does anyone have an explanation for this? I have no idea how I'm losing rank despite improving on scores and getting great scores on new songs.

Please help!