There is a lot of speculation going on regarding the tone change and reshoots. But let's look at the facts we do know.

Snyder, after screening a rough cut of Justice League for fellow filmmakers and friends, wanted to add additional scenes, so he brought Whedon on board to write them. But as he prepared to shoot the scenes in England, Snyder realized it was not the time to leave home. “The directing is minimal and it has to adhere to the style and tone and the template that Zack set,” says Emmerich. “We’re not introducing any new characters. It’s the same characters in some new scenes. He’s handing the baton to Joss, but the course has really been set by Zack. I still believe that despite this tragedy, we’ll still end up with a great movie.”

Snyder picked Whedon to finish his film. They were already adding scenes and writing new material for the reshoots even before Snyder left the project. All the things were in motion even before the trailers and reports. The change in tone for Cyborg was probably just a result of the screening, maybe he needed a bit more personality, more interaction with the rest to really bring the character to life. Small little details that make or break a film of this magnitude.

Look beyond all the fluff pieces about the film and just look at the hard facts that are out there and you will start to not worry as much. There is a lot of noise out there that just leads to meaningless and misinformed speculation.