It's the VAR rules. The referees must let the play end to call the offside. If it's a goal, then VAR checks it, if it's not a goal it will be decided by the referee on the field.
It really doesn't make much sense, when the offside is clear and far from the goal. But, unfortunately, the rules currently exist.
It totally does not make sense yet I love VAR despite having failed me many sport tickets.The reason is that now we have a way to replay the action and the referee to see again the action and to decide cold headed,not with the heat of the action that he is following in the game.It has decided and impacted many games,some for the worse but a lot more for the benefit of the teams which without a VAR would have the goal disallowed and not having a look at it again and that is why I love VAR as it most of the times save teams from injustice done unintentionally or intentionally by the referee.
I remember a game where he saw several times the VAR in a league I don't remember and I saw that he did not want to give it a goal yet he was forced to give it a goal as everybody saw it was a valid goal.