Dubov vs Nepomniachtchi: 1.Nf3 Nf6 2.Nd4 Nd5 3.Nb3 Nb6 4.Nc3 Nc6 5.Ne4 Ne5 6.Ng5 Ng4 7.Nf3 Nf6 8.Ng1 Ng8 9.Nc5 Nc4 10.Na4 Na5 11.Nc3 Nc6 12.Nb1 Nb8 13.Nf3 ½ - ½

You can't identify any particular move as a blunder, yet both players lost (0-0 is the official score).