That happens with every movie that gets a trailer rushed shortly after filming for things like Comic Con. Guardians of the Galaxy and the newest Fantastic Four were big examples of that happening, they looked like different movies between their early released teaser and finished product.
People are trying to tie in Suicide Squad being more comedic because of Batman vs. Superman being serious which isn't true. Trailer 2 for Suicide Squad was released months before Batman vs. Superman came out and that was the goofiest trailer of the 3.
Some new Suicide Squad scenes were being filmed the same week BvS came out and people were like "they're filming new jokes because of BvS being dark" no dumbasses this was scheduled way in advance, you can't get Will Smith on 3 days notice to film new scenes because you want to add jokes lol