I'm watching it again on Max and it really shows how tragic the DCEU is.
This timeline Flash visits, is doomed to be destroyed by Zod because there is no Superman. Super Girl is not enough because she doesnt have the care for earth that clark has and wont go the level Clark did to protect it. It actually validates one of the biggest complaints (and linchpin of hate) of the DCEU.
It also prooves that Batman was correct in the World needing Superman. Wich also shows that like this earth, the DCEU is doomed to the nightmare timeline.
Another interesting thing I though of is that Batgirl is still cannon because its not just a slighlty different timeline than what we got in the final version.