The DC's cinematic universe's The Flash movie has a big cast, but fans are excited to see the new look of Sasha Calle, who plays Supergirl. She's sporting a short black haircut which has many pointing to the (alternate) Cir-El iteration of Supergirl.
Cir-El was a human girl who was given powers and sent to kill Superman by Brainiac. There's also the possibility that they're going with a new look for Kara (the original Supergirl) when one considers the originality of Aquaman's new design and Batman being a killer in the DCEU.
The DC Extended Universe is its own story that some are hating, but there are many who love the originality of it because it's hard to predict what will come next. There's a sub-set of fans who don't gravitate towards the "campier" or "brighter" superhero stories and prefer the darker tales that DC Comics is known for in some cases. Deadpool, The Boys, Logan, and Invincible all are great examples of violence not preventing a show from doing big numbers.
The Flash may not go down the route from the comics and right now there's no official confirmation as to what the story will be. Rumors have been speculating that this will be a "Flashpoint" story in which Flash reverses the timeline and changes a number of things in the DC universe. These include Batman being the one to die in the alley and even a war between the Amazonians and Atlanteans. The storyline was loosely adapted for The CW's The Flash television series, albeit without the major elements previously mentioned since the related characters had not appeared on the show.
Many are hoping that The Flash will be the film to "fix" DC's mistakes that are preventing them from being on par with Marvel's cinematic universe. Typically, fans think that DC has been better when it comes to making video games, animated shows, and animated movies but has been lacking in the live-action department. Some arguments include the lack of continuity, a convoluted story, sub-par fight scenes as well as lack of character diversity, as was the case with the handling of Ray Fisher's Cyborg.
There are also those who refuse to give DC a chance. After the mistreatment and racial discrimination against Fisher, the drama behind Zack Snyder's Justice League dispute with Warner Bros., and the lack of a solid lead producer in the realm of a Kevin Feige, many don't see a revival of what DC used to be.
The Flash is currently in production and slated for a November 4, 2022, release.
Source: Sasha Calle/Twitter