"Doomscroll doesn’t necessarily have to be about negative news. "

Taking the name literal, it does. But sure, endlessly scrolling positive news while being in a zombi state in reality, is doom as well.

Insofar as we can actually definite Internet terms, (like enshittification, which has a specific meaning, but Cory Doctorow himself told me not to word police other people about their usage of it.), doom scrolling refers to the fact that attention is sacred, and technology has hacked our attention spans, like a sophisticated laser pointer dot and a cat, so the doom is in losing unplanned hours to content, whatever that content is.