User blog comment:TimeShade/The Crisis Has Arrived/@comment-30206523-20200115051301/@comment-30206523-20200115052423

Jourdon, the Earth-19 and Earth-2 of the original multiverse were destroyed, and the original multiverse wasn’t restored, but instead a completely new multiverse was created, and therefore Earth-19 and Earth-2 had to be replaced, as it was stated multiple times that a destroyed universe could not be restored. Prime-Earth isn’t simply Earths 1, 38, and BL merged, but a new universe made by Oliver that is supposed to contain parts of the original multiverse, but also has features that were not a part of any of these Earths, such as the DEO being a part of LuthorCorp. So to answer your question, the show said that Earth-19 and Earth-2 were replaced.