A lot of people have some serious problems with new display chipsets, myself included.
FRC (Temporal Dithering) is a much bigger problem than people think.
PS3 is the BEST display for me, since it uses nVidia chipsets which have ZERO temporal dithering. Xbox One and PS4 both use AMD chipsets which use heavy temporal dithering by default.
Sounds like your Fire Stick uses temporal dithering. Sorry, man.