Not quite.
Shadowlands is another realm of existence. It isn’t fully clear (at least not to me) just how much a warlock can consume or corrupt/deconstruct a soul, and I’m not even sure Blizzard has delved into it completely.
If you “die” though in Shadowlands…it’s permanent. Ultra permanent. Ursoc was killed in life and his soul went to shadowlands…where his soul was then killed again. Again, if you read and pay attention to quests and text, you’ll see this is essentially perma death.