I have seen several posts now of people getting the Did Not Finish (DNF) tag counted towards their games.
I have noticed, like others, that this happens not because we ragequit the game while we are playing.
This bug occurs when the match is over and we are in the post-game lobby with all the people of the finished game. When we go back to the menu we get the DNF tag for leaving the match, while we actually left before the new match actually started!
So all of us are set as ragequitters while we actually weren’t there to start with. We left before the match started so we should not get the DNF tag.
tl;dr - Bug: You get the Did Not Finish (DNF) counted when leaving the post game lobby