I put my Karlach playthrough on hold for months due to the bug, which I reported to Larian long ago, that Minhtara could not be talked to after Karlach killed more than two dozen guards to recruit her. Patch #6 fixed the issue, even though I didn't see this fix get mentioned in the release note.
The first line that Minthara said to Karlach after months of silence was the reveal of the precise connection between the guardian, the elder brain, and the prince.
What a surprise! However, I dismissed the line as an inappropriate reveal or a bug. I thought she was supposed to be an insider, knowing much more about the truth than the player has been able to by this stage of the game. It's no surprise that she is able to have learned of each major party's true identity as well as their connection. I checked the quest log. The prince has been mentioned in the log already. Minthara also mentions that she once even fought alongside with the General. Definitely, she knows a lot more at the time.
I agree that this line may be better reserved for the early part of Act 3, as it feels like out of nowhere in the middle of Act 2. However, I don't think it spoils a new player or any player if they can learn more about the truth from an insider companion.
After this line, Minthara further reveals her knowledge about all the existing companions (except for dead Halsin and the main character Karlach herself). And it's nice to hear her talking about them.
She has implicitly answered my long-time personal question, why Karlach, being an upbeat good girl, can and should work with a crazy fanatic Minthara for the rest of the game. And her implicit answer is satisfying to me.
