There can be no such thing as toxic positivity. Your doubts are toxic, yes. But positivity can never be toxic. Life IS utterly binary and clear-cut in this respect, there are no grey areas, no nuances. There is an absolute good and it is joy. And it is 100% a personal choice, regardless of circumstances. Once again - it is the only ONE thing over which you have any control, at all times, no exceptions. You can always choose to be happy. AND that's enough!
Leaving out people with e.g. clinical depression, this is still only true for some people. The rest don't believe that they can simply choose to be happy regardless of circumstances, and therefore they can't. I don't think we get a choice in the matter: either we're lucky to be in the first group who know it intuitively or figure it out or come across the idea somewhere, or we aren't so lucky.
Which is why they are depressed. They choose (over and over and over again, many times in each hour they make this CONSCIOUS CHOICE) to find this insulting, instead of empowering.
I am leaving out no-one. Joy is absolutely accessible to every living being, at all times, under all conditions.