Yes, seems like it is AS 12 'Losharik' (Project 1083 1), its 'mothership' is a former Delta III with a changed back, maybe the 'Lorenburg'.
https://news.usni.org/2019/07/02/14-...lear-submarine
Capable to dive to 6000 meters, due to its interior pressure-resistent ball design ('losharik' is a russian cartoon horse consisting of balls)
A terrible accident, feeling sorry for the sailors and their families.