Star Trek: Picard is not a series interested in the familiar, and frankly childishly-written, paradigm of characters who always do the right thing in the end. It presents us with characters who are morally compromised, who are traumatized, who do not always have enough social or literal power to do the right thing, and who sometimes do things that are awful or questionable. Simply put, this is not Star Trek: The Next Generation, where Picard gives a speech about how he's so morally superior and puts foolish aliens in their place before warping off to the next adventure.
It is also not a show interested in the trite idea that life is pain, that grimdark=superior, or that there's no such thing as good and evil. Simply put, this is not Battlestar Galactica, where the pain and trauma and moral compromise are so foundational that the series ends by concluding that society literally has to be dissolved.
Star Trek: Picard is a show where fucked-up people are doing their best, and sometimes they're wrong, but where they are on balance making the world a better place in spite of their flaws. Yeah, Seven kills Bjayzel. She does so in the context of Bjayzel living in a society without the rule of law, engaging in a science-fictional equivalent of human trafficking and ongoing slow-mo genocide against XBs -- so, you'll forgive me, but I'm not entirely persuaded that it's immoral to kill war criminals if there is no rule of law.
She also saves Elnor and the crew of La Sirena and thereby helps save the galaxy from the Admonition Makers, and she's dedicated her entire life to bringing stability to a region of space forsaken by the Federation.
She is, in other words, more complicated than just being good or bad. This is a show that is written for adults, not for children who need rudimentary morality lessons.
