According to developer CD Projekt Red, the delay in release for Cyberpunk 2077 is purely due to issues faced on Xbox One and PlayStation 4, with the PC version apparently ready to go.
The game has suffered a significant further delay into December, leading to a significant backlash, and even serious abuse and death threats from gamers. According to CD Projekt Red, the complexities of developing and testing for nine different platforms (PC, Current Gen, Next Gen, and Stadia) has lead to serious difficulties.
Adam Kiciński, a CEO at the company, stated specifically during an investors call that the Xbox One and PlayStation 4 are the two consoles at the heart of the delay.
The game is ready for the PC and runs great on the next-gen consoles, and could be shipped on the scheduled date on those platforms. However, even though the game has been certified on the current gens by both Sony and Microsoft, some very final optimization processes for such a massive and complex game require a bit of additional time.
He stated several times in a follow-up question that the PC version ready, and would, if released alone, make the November 19th release date, but the company has decided "these extra three weeks will enable us to get more things ready to our satisfaction."
According to Vice President Michal Nowakowski, during the same call, the issue with the current-gen consoles is optimization related, although he did suggest that there will also be an opportunity to fix other bugs and quality issues.
The game is now slated for December 10th, but given the sheer number of delays, even CD Projekt Red are stating they're "not comfortable, but confident" about the new date.