A goalkeeper’s first move for any dive is a step toward the shot. It’s the equivalent of a kicker’s plant foot. You can’t generate any power into a dive with a sidestep, nor can you get low (your entire body would have to pivot around that planted foot instead of your hips). The knee on the other side is driven up, over the bent leg. The combination of the coiled energy created with the step toward the shot and swinging the opposite leg up and over is what creates the power. This is why keepers never land on their stomach (that and pain)- the most efficient and energetic motion will have you land first on the back of your shoulder.
On a penalty, these new rules make it impossible to generate power at the moment of the kick. You need to take that step forward into your dive a moment before the plant foot lands or the ball will be by you before you start your dive. This necessarily pulls your other foot off the line. While the rule hasn’t changed, per se, interpreting it so literally is destroying any chance of making this anything other than an uncontested kick from 12 yards.
I’ve read enough about sexism in pay, running up the score, and celebrations. I can’t imagine FIFA making such drastic rule changes take place days before the men kick off their World Cup. The combination of VAR, incidental hand/arm contact, and goalkeeper scrutiny has created a monster FIFA didn’t consider and it’s having a horrific impact. Penalties are a 75% chance in the men’s game. Due to size alone, they must be a higher percentage for women. This interpretation of the rules for keepers is handicapping their fundamental ability to generate the power required to get to the bottom corners of the goal (ignoring the fact that that another third of it, the top two corners, is inaccessible at all).
In a just world, FIFA would acknowledge this mistake and plan accordingly moving forward. We all know that’s laughable. We’ll carry on like this for years until the uproar gets too loud to ignore.