This one might be a little spicy.
TLJ’s portrayal of depression through Luke is offensive to people actually struggling with depression. This notion in the film that depression caused by trauma makes it understandable for you to abandon your family and become a bitter, callous, generally crappy person to others for no good reason, is neither accurate nor helpful to depressed people, and doesn’t reflect how most people actually cope with mental health issues. TLJ Luke’s depression is a cartoonishly exaggerated form of depression written in a way that shows a lack of understanding of what it actually is and how it affects people. It conflates depression with being an awful person.
And yes, he does “redeem” himself at the end of the film, but it doesn’t come off as a genuine return to goodness, since he’s still trolling Kylo, the man he once traumatized, and generally still acting snide and sarcastic, while not making any attempt to right the wrongs he committed towards him.