One of the "joys" of online blitz stems from frequent losses to players that haven't the vaguest idea of proper play. Some things you're just born knowing, but some folks don't get. Of course, I'm spouting nonsense.
Nevertheless, the concept of mined squares is one that players should know by the time they get into the C class (1400-1599). Alas, some do not.
This position is a case in point. I have Black and am on move. Because I understand mining (c4 and e5 are mined), I play my king to b4 (Kb4) and console myself with the draw.
My opponent, however, has somehow achieved a 1766 online rating without gaining the knowledge of kings and pawns (or is using premove, or ... ?) and plays Ke5?? Now I have an easy win--the sort I expect my pupils in elementary school to win against me upon demand.
Now that my opponent has moved to the mined square, the corresponding square is safe (and required to avoid loss), Kc4-+.
Remember the resulting position: it is a classic zugzwang; the player on move will lose.