my story: i took the same USA-CDG flight twice over a 6 months span.

the second time i took it (January 2023), all passengers in my plane were able to connect to next flight without security screen. i didnt get that option 6 months ago.

I was very happy about bc it was a delayed arrival and i was really dreading the line in security screen. there is an AF agent standing at the fork directing passengers

i was connecting to a non-schengen destination. after the fork, i find myself immediately in L, which is where i need to be because that's where the gates are for non-schengen countries. iirc if you are heading to schengen, you walk the same path too, but my guess is at some point later, you will leave L and find yourself in some other hall and that's where you will see the passport control

looking at the map, after L, you will hit M. so i guess K is backtracking and a bit further than the rest
https://www.parisaeroport.fr/en/pass.../terminals-map