Apparently something kicked off on GB the other night with the alleged return of ohffchibnall, who leaked much of this series to the fandom. People suspect this might be an alternate but hacked account, buta whole page of posts and replies were deleted after trolls accusations flew...also the post was described as 'garbled', though someone deciphered the new leaks, so here they are...take with a grain
Source: Zurgatronic, GB (deciphering from ohffchibnall)
from what I could decipher from the somewhat garbled way they were written:
The Doctor gets cyber-converted. Captain Jack reverses time to undo this, but in the process Thirteen's consciousness is sent back to Ruth, which is how we see all the Timeless Child stuff unfold. Her consciousness then returns to Thirteen's body. The Cyberman plot remains unresolved and the companions are abandoned on Mondas. I might be forgetting some details as it was written in a very confusing way.
I wouldn't put much stock in it, especially as Chibnall has outright said Jack is not coming back in S12 (my guess is we'll see him in the Dalek special).