I hope not to get into any deep discussion of PWM and get banned and have the thread locked. I have clunky shoes, but I am trying to tread lightly.
What you are seeing with your phone's camera cannot be PWM, unless it is not the AA converter:
I don't know him personally, but I have enjoyed many of his posts, and have an impression of the man. I believe if you held a gun to McGizmo's head and ordered him to lie to you, he would defy the order and tell the truth. Maybe that's an exaggeration, but I believe him to be entirely honest about his product.
Phone camera test is not definitive, or can be misinterpreted. CPF member
jon_slider has some threads that explore and explain what the camera phone is detecting from constant current circuits. I would suspect it is ripple, not PWM.
Also, things unseen can adversely affect you, so it is a poor argument to suggest PWM is harmless if you cannot see it. You cannot see or smell carbon monoxide, this does not mean it is not unhealthy to breathe it. You cannot see the bacteria that infected your wound, but it does not mean it will not eventually take your limb. There are many counter-examples that invalidate this often repeated argument, "can't see it, so it is harmless."
It is difficult sometimes to trace ill health effects to their source. Many claim to be unaffected by PWM, but it is unclear, depends on how the light is used and for how long. Eye strain or headaches can be caused for any number of reasons. That is what makes PWM so insidious, IMO, because it is difficult to determine it is the source of any problem.
PWM was introduced into LED drivers to solve the problem of tint shift in lower modes, which it is claimed to solve, and in theory, it should, but I still see tint shift sometimes with PWM lights in lower modes. PWM circuits are also less expensive to design and manufacture than fully constant current circuits, and less efficient. It is only through the evolution of LED drivers and users' experience that these details become evident. With PWM, YMMV. If it isn't something that bothers you, don't worry about it, but if you suspect PWM bothers you, avoid it.