User blog comment:MakeShift/The Crisis and its impact on the Arrowverse Wiki/@comment-31524712-20200124154231/@comment-5774336-20200129023447

We know that there is still a Multiverse following Crisis because of the parade of alt-earth cameos at the end of the final episode of the crossover, and that either through Martian Manhunter's abilities or through tech to replicate his abilities (Shown on Arrow S08E09) that most allies and team members of the different shows know what happened during Crisis. But if you've been watching Lucifer, he has never once referred to Constantine OR Crisis on his show. So prior to Crisis Constantine and Lucifer had dealings, yet Post-Crisis as far as we know THAT Lucifer has no idea who Constantine is.