Yeah, it's frustrating and kills the flow of a game.

And apparently the offside rule was introduced in 1863 by the then newly formed Football Association (FA), stating that a player is offside unless three players from the opposing team are in front of him. This rule was changed in 1925, reducing the number of opposing players required to be in front from 3 to 2 players. In 1990, this rule evolved again into what we know today as the modern version. This change stated that a player is considered onside if he is level with the second to last opposing player.

@Ryo1 With VAR it is now very unlikely that players are level. There is often just mm either way.