*SPOILERS BELOW*
She was NOT sidelined. Briefly got my hopes up when she was attacked near the start. But seriously, I can't imagine how her role could've been any more prominent short of being lead herself.
Studio, trying to hide her presence and hoping to convince movie goers she was not in the movie or barely in it by giving her whole 1 second in trailers was epic.
It was misleading, it was basically lying to audience and those fanboys. They tried to appease both sides and failed at it. They could not cut out Heard completely and too obvious. Because woke press would attack them. So they cut off her time significantly. And in the end she was no satisfied by it and fan boys were not. And fanboys were not fooled by that trailer. They still did no come.
In the end none of that actually mattered because that movie would flop no matter what. Because it was bad, people are tired of superhero and there was no point since DCEU was over anyway. Wonder Woman 2 flopping and being hated was the first bell that DCEU is dying. People were over it with that Justice League movie.
If people in WB would have any brains then they would not announce rebooting until Aquaman 2 would come. And leave people to believe this is relevant universe. Then start casting next Superman and dump them all. Flash and Aquaman 2 would get a little more money.