I had this starting around the beginning of COVID. Was it COVID? Did I get COVID at all? Plausibly, but not definitively. Did I get it at that time? Almost certainly not as I stayed isolated and got tested whenever I wasn't. It could be aging but I think a lot of people chalk things up to aging that are actually due to non-aging-related causes - you just accumulate more past as you age so you're more likely to have encountered whatever the cause is. I did go camping several times, once in a region known to have Lyme, without being vaccinated, but that was years after I started noticing chronic fatigue. Conclusion: I really don't know.

At least some of my cognitive decline is surely related to my attention span, which is not aging-related at all but more to do with the modern information-flood environment. A few minutes ago I misread "scripted" as "sculpted" in an HN comment and then stopped to reflect why I did that. It wasn't because I can't read, but rather because I was skimming over that comment really, really fast, because that way I can view more comments.