User blog comment:Itamar20112/Arrow 8x01 - A good episode, but kinda breaks the Arrowverse/@comment-31722073-20191018003407

The filters are simply a way people use to separate times and worlds, flashes are sort of sepia so we recognize its not now and darker, and the Flash people used a yellow filter so we know whats on what world, but when everything is on one world it doesn't matter.

Earth-Two was destroyed because we know what Earth that is, it is the only Earth that isn't from a show that includes people we legitimately care about, and so destroying it is a sucker punch to the gut, Harry and Jesse dying will be mentioned over on the Flash because that's where they matter, I think that destroying Earth-2 right at the start was the shock we needed, lest we think all the Earths that matter will make it out (oh and Gypsy is still safe on Earth-19 for now).