I wasn’t struck so much by the precise skirt length; but by the overall emphasis on uniforms in a rows-of-lockers style high school setting.
Does the US have schools with uniforms, some public, many private? Sure. Are the iconic rows-of-lockers media depictions usually of those schools? Not so much, plenty of private schools have lockers as well; but it’s more of a big public high school look.
Looking at it as an American; it seems like someone is playing an American’s stereotype of how British Public school dresses in front of a (substantially accurate) perception of how an American Public school is probably constructed.
Taking a few inches off the skirt doesn’t help the realism; but I assume that’s an influencer tax.
