This is such FIFA horseshit.
I think I posted above about how I thought that penalty shootouts were going to be the perfect place to highlight the problem with the new enforcement of line calls using VAR. FIFA has taken the chicken way out, taking away the biggest objection. But there's no justification. If it's against the spirit of the game and warrants a caution then it's against the spirit of the game. To wait until after players have accumulated yellows for this infraction in the group stage and then put a bandaid on a bigger problem is just horseshit.
Edit: Also, can you imagine a game where a keeper gets a second yellow for being off the line during regular time, and her team has to play on 10 women, only to have the opposing keeper do the same thing in a subsequent shootout with no penalty except a rekick.
Also, if it's an infraction warranting a yellow during run of play, why is it only reviewed by VAR on unsuccessful goal kicks? If it's unsporting, then it should be reviewed on all penalties including successful ones.
Obviously, I don't really believe that. But I do believe it's all horseshit. Let the ref call it. She's standing right there.