I encounter many times following situation:
One player has a lead in power and such a good hand that the other player cannot win or that one player is about to reach the winning threshold of 40 or 80 points but takes a long time for his turn while the other losing player already knows that he/she won't be able to catch up.
Sometimes the losing player asks the winning player to finish (by turning Crow or to stop pulling/playing cards as the winning one has already crossed the threshold) in chat but the winning player does not see it.
So I suggest following:
Implement a function that each player can activate when it is the other one's turn. This function is "asking for an agreed concede" and the asked player can either accept or reject the proposed concede of the asking player. If concede offer is accepted the asked player will get a win with all rewards. The asking player will not get a time penalty irrespective of when the offer was dropped and I suggest to give no rewards if the match was conceded too early like now and only a white reward after some time just like now.