But... they so obviously didn't offer an extra ending, it's literally just the "she goes to Avernus" ending, but with more detail... Calling this a different and new ending is disingenuous in itself.
This is exactly the problem I have with the updated ending. It's just an extended view of a pre-existing ending. The way they were talking, I thought Larian meant they would provide a brand new ending option that would be more satisfying and fulfilling for Karlach fans that really wanted a happy ending for her personal story. To say that this ending is what she "deserved" is just hurtful. I don't think that's what she deserves at all. It's not a good ending.