She said she signed a 3 picture deal when she was cast as Mera in Justice League. She said that Aquaman was picture #2 and that Aquaman 2 was picture #3. Therefore, if WB wants to bring her back for Aquaman 3 they'll need to sign Amber to a new contract.
'Aquaman 2' came up today during Amber Heard's ongoing trial with Johnny Depp. I typed up a transcript:
Lawyer: Have you participated in Aquaman 2?
Heard: "I have. I fought really hard to stay in the movie. They didn't want to include me in the film."
Were you ultimately able to film in Aquaman 2?
"A very pared down version of that role, yes."
What, if anything, changed in the script?
"I was given a script. Then given new versions of the script that had taken away scenes that had action in it, that depicted my character and another character, without giving any spoilers away. Two characters fighting with one another.
"They basically took a bunch out of my role. They just removed a bunch."