Earlier quoted context omitted.
I'm sorry to read this, I also have a similar same situation with my father. He's in his late 70's and a year ago bought himself an iPhone. He now spends ~4 hours a day reading a tabloid newspaper app, which has endless content. His attention span has fallen noticeably and he can't keep up with conversations that happen in the same room while he's "scrolling". When I visit he's on his phone, and we go out for a walk…
Similar with my father but he's got a dumb phone and browses on his laptop. When we have conversations with family he seems to always tune out after a few minutes and goes on the computer. His whole world view has been flipped upside down by conspiracy and hoax content. We've talked to him about not mentioning that stuff while we're over but it seems to be affecting his happiness nonetheless.
And even more, I wonder if it can be cured. I think it ties into how socially isolated men are, especially old men. Once you retire and your work social network is gone, their only social ties are online. They need to identify with a community, and I guess there is something appealing to being in a conspiracy in-group. It's just impossible to pull them out, because you have to replace that group with something else. And there's just nothing there for them.