The Flash Season 6 Review: 7 Ups & 3 Downs From 'Death Of The Speed Force'
Downs...
3. Narrative Inconsistencies
Nash Wells' not-so-subtle attempts to make Cisco realise that he's been struggling with visions of dead Harrison Wells doppelgangers prompted an interesting conversation about how no doppelgangers would be able to exist on Earth-1 because they'd end up being killed by neurological degeneration.
While this might lend itself nicely to what went down with Beth and Alice on Batwoman, it doesn't explain why Earth-2's Laurel Lance (a.k.a. Black Canary and formerly Black Siren) remained alive and well following the Crisis (and will continue to do so when Green Arrow and The Canaries is hopefully picked up) or why the other Winn/Toyman was fine over on Supergirl.
This could be down to the unbelievable hoops that the Arrow writers forced themselves to jump through instead of just admitting their mistake by killing the original Laurel Lance and reviving her or it could be down to a miscommunication between the producers of all the shows. Either way, something doesn't add up here.