She realizes she wasn't pushed off the ferry in the first place—she jumped intentionally as part of a previous failed plan to disappear, but the ferry’s propeller caused her memory-wiping head injury. Closing the San Francisco Chapter
She fakes her death to escape her life in San Francisco. Watch surface 2022 s01e08 720p web h264-ggez 1
Before vanishing, Sophie leaves a parting "gift" for those she left behind: She realizes she wasn't pushed off the ferry