This wasn’t Canadians! Stop telling lies! It was clearly The Joker. Look, he’s even painted the bat-symbol right there! He’s trying to taunt Batman!
Wouldn’t that mean it’s Batman?
When has Batman ever left his own symbol? It’s used by others to summon him.

to summon him

is he like a vampire or something?

I mean you only see him at night and he dresses like a bat… He also lives in a mansion, has a cave, and stays up all night.
He puts his symbol everywhere. Like everything he owns is covered/made out of that symbol. Certainly that would be his tag/signature right?
He paints it with plastic explosives.
Oh you’ve gotta give No Man’s Land a read.