Well, non-ionizing radiation (NIR) cause cancer has being debated such as this [1]. It wouldn't surprise me that it will be a bit like the Roundup/Monsanto situation. I don't blame people wanting to use these kind of protection just in case.
And iPhone also had this in their Product Information Guide:
"When using iPhone near your body for voice calls or for wireless data transmission over a cellular network, keep iPhone at least 15 mm (5/8 inch) away from the body, and only use carrying cases , belt clips, or holders that do not have metal parts and that maintain at least 15 mm (5/8″) separation between iPhone and the body."
And iPhone also had this in their Product Information Guide:
"When using iPhone near your body for voice calls or for wireless data transmission over a cellular network, keep iPhone at least 15 mm (5/8 inch) away from the body, and only use carrying cases , belt clips, or holders that do not have metal parts and that maintain at least 15 mm (5/8″) separation between iPhone and the body."
1. https://www.sciencedirect.com/science/article/abs/pii/S02697...