Per new tweets from international PlayStation channels, including PlayStation Europe and PlayStation France, there’s an additional map available now in Survival Mode in Call of Duty: Modern Warfare, which is exclusively on PS4 till October 1, 2020.
The tweet from PlayStation EU is a video showcasing that St. Petrograd MP map is now part of Survival mode. At launch, Survival mode only had 3 maps to play from.
Activision and Infinity Ward have not officially announced its introduction into Survival mode in Call of Duty: Modern Warfare yet, but it appears the map was added when Season 1 started.
As noted before, Survival mode is exclusively on PS4 till October 1, 2020.