A source tells ET, "Gaga has been laying low because she is so focused on her work. She's completely immersed in the Joker sequel and a lot of her energy is going toward that. She is totally in the zone and wants to kill it."

The post shows a black-and-red video of Phoenix and Gaga's shadows joining together, along with the caption announcing the sequel's release date, Oct. 4, 2024 -- exactly five years after the original's release. 

Gaga is speculated to take on the role of the Joker’s co-conspirator, Harley Quinn -- his psychiatrist at the asylum who becomes his partner in crime. 

In December 2022, ET caught up with Robbie where she gushed that she's "so excited" for Gaga to take on the famed character. 

"I think she's going to do an amazing job. I'm so excited, it's all I could've ever hoped for Harley was that she would become one of those characters, kinda like Batman or Hamlet, that's gets handed from actor to actor, everyone gets a go at playing them," Robbie said. "So, I think it's just credit to her as a character that people want to see her in multiple iterations. I'm excited."

Joker is the origin story of Batman’s arch nemesis, Arthur Fleck, which follows as he goes from comedian to villain. The film grossed an estimated $1 billion at the box office and earned Phoenix an Academy Award for Best Actor. 

The script for Folie à Deux was written by Todd Phillips, who is also set to direct the film and headed up the 2019 movie.