**Quoted from the Article** :   
> A decade after Ultron's MCU story seemingly ended, he is seen haunting Vision in the first VisionQuest trailer. Ultron tells Vision that the titular character has become *"a ghost haunting your footsteps."* The trailer also includes Vision imagining other familiar characters and events inside his head.  

 > It was explained by Paul Bettany during the NYCC panel that Red Vision gave all of his memories, including his memories from inside WandaVision's hex, to White Vision. In the upcoming show, White Vision is having a difficult time connecting all these memories together and is on a journey to find his true self.  

> The trailer teases what this struggle will be like for Vision. The human Edwin Jarvis (James D'Arcy) was the basis for the J.A.R.V.I.S. artificial intelligence created by Tony Stark that played a vital role in Vision's creation. This truth becomes muddled in Vision's current memories, though, as do his memories with the AI F.R.I.D.A.Y. and E.D.I.T.H.  

> Ultron's line suggests that he is more than a memory in VisionQuest's story, though. His understanding of what is happening to Vision indicates that the villain has truly returned and will play an important part in Vision's journey to connecting his memories.  

Related Tweets (from Discussing Film) about what's seen in the trailer :  
https://xcancel.com/DiscussingFilm/status/1977081726779506776  
https://xcancel.com/DiscussingFilm/status/1977078794616971694  
https://xcancel.com/MarvelLeaks22/status/1977089964405146105

ULTRON warns WHITE VISION about reconnecting with VISION's past memories of WANDA in the Vision Quest teaser footage: "You're a Ghost haunting her footsteps"