Current research suggests that declining attention is most likely caused by an expectation of quality rather than actual personal issues. Condensing information is a valuable skill an people do not have time for middle length content just to be disappointed.
This article at bbc references the time as misguided.
This article shows that measuring attention spans is not that easy and our world is more distracting. Not a good think but it does not blame the people.
This Booktuber got some sources and a nice way of presenting it.
One might argue I am splitting hairs and I do not blame you if you think that. I hope some people think harder about their focus and how to find some calm moments. Yet I say that while searching up sources because I got a mobile notification.