Don't remember ever seeing something like what happened with VAR in Lazio - Sassuolo match. Immobile put the ball into net, but the passer seemed to be clearly offside by several meters. And ref Irrati immediately ruled the goal offside.
Then apparently VAR ref somehow considered it wasn't offside and after a few minutes pause Irrati pointed to the centre circle indicating that a goal had indeed being scored. It was hard to believe it wasn't offside, but maybe the camera angles had been very bad. Lazio players celebrated the goal for a few minutes more.
Then as Sassuolo was about to restart the match, Irrati pointed to his earpiece that he was listening to something and prevented resuming the match.
And indeed, he then ruled that it had been offside after all and his initial judgement had been correct, and the match continued with a Sassuolo freekick. Maybe Irrati just misheard what the VAR ref had said and that caused the confusion.
In the end it didn't matter as Lazio scored two goals and won the match, thus postponing Napoli's title celebrations until tomorrow at least.