You can read more about the KGS system if you want
https://www.gokgs.com/help/rank.html
and
https://www.gokgs.com/help/rmath.html
and
https://www.gokgs.com/help/anchor.html
My feeling is that it’s much more chaotic than OGS or any other system. They supposedly have a set of anchors, players that they think their ratings are very stable and then base everything else off of that.
I feel like the net result ends up being that your rating jump all over the place even from inactivity.
There was a joke I saw a while back on how to become 1d if you were stuck at 2-3kyu
A few of the other replies to the post also were examples of plays stopping playing and their ratings drifting noisily upwards.