This isn't an issue of canonicity, it's trying to put forward and argument that Peacemaker doesn't even count as a DC product which is absolutely ridiculous.
Joker was a movie but isn't part of some EU, so does that also not count as a DC product??
Honestly I'm getting pretty sick of all the extended universe stuff and would rather all these comic book movies and shows start being their own thing and not be shackled together.
It's a James Gunn/HBO product a hundred times over before it's DCEU.
Still not DCEU which is what this film is trying to be.
That would be great, but it's not what this film is trying to be, so I'm very comfortable having doubts about this film before I know anything other than a few shots of a costume.