At 1% unwinnability, I think that almost nobody would notice the existence of unwinnable games merely by playing, but having the knowledge of the exact percentage of unwinnable games might start to diminish enjoyment.
Solitaire, where 20% of games are provably unwinnable from the start, absolutely suffers from this effect, because even when a player loses a winnable game they will be tempted to blame the game rather than themselves, fostering resentment.
If a game was provably unwinnable 80% of the time, then that would be either a damning indictment of its design or an indication that the value of that game is to be found in some aspect other than winning.