I think these are two separate questions. Is Brown disgruntled and would it be smart to trade Brown for Durant whether he is gruntled or not. Durant is a great player. If you want him on the team and think he can stay healthy and take the team over the top, then you trade Brown for him. Whether Brown hung out with Kyrie or not would not factor into my decision at this point in time.
I would not want to trade Brown for Durant though. We are a good young team that may be a few roster tweaks away from another trip to the finals. BKN is not going to trade Durant other than for a massive package that will probably turn out to be an overpay. We don't need to overpay to get Durant.
As I have said earlier, next off season, maybe you look more closely at where Brown wants to be or even at the trade deadline in 2024. And at that point, if it comes to that, let someone overpay for Brown. Don't use Brown as part of an overpay for an aging, emotionally uncertain, player like Durant.