soul is gone the moment you undergo ceremorphosis? Basically, everything from you is gone - from soul to flesh and it's just the tadpole eating your memories and present them as you are said person. Karlach is not Karlach anymore; just a tadpole that took her memories... Withers says illithids have no soul. And he knows this stuff for obvious reasons.
Not gone, fully destroyed. Not really a big distinction for narrative purposes but it means normal methods of resurrection can't work. Even a Wish spell will struggle to bring the real person back in the tabletop based on DM discretion because Wish will typically replicate existing magic where it can, but reconstructing a soul destroyed by ceramorphosis is magic the likes of which couldn't be done with magic higher than level 9 that Mystra made impossible to use, and Wish is ONLY level 9.
