how to enable xfinitys’ picture in picture on iphone 13

why does the picture in picture option not ‘lit up’ so one can click on it and goto the guide or whatever and still watch the program thats running…my old iphone 6s plus with ios 14.4 has it and its available and it works, always has…but this new iphone 13?…one can see the  pic in pic icon there but its faded, not lit up for choosing?…why?…how do i get it to be lit up and available?