What is the point of this code I found?

// Is this like cat abuse?
footer.wp-block-template-part {
:where(.wp-block-group.has-background) {
padding: 0 2.375em;
}
}
// Should be this
footer.wp-block-template-part {
.wp-block-group.has-background {
padding: 0 2.375em;
}
}