The story isn't about the number of people who develop severe cognitive problems following Covid; it's about the number of people complaining about "brainfog and forgetfullness". People follow trends, so if it's trendy to talk about food intolerances, the media will flood people with stories about intolerances, and people will talk to their friends and associates about their intolerances, even if they only have a mild dislike for a food. ADHD is not a newly-developed condition, but people didn't talk about it until it became trendy to do so (and the term was invented and became popular). If lots of people started talking about "brainfog and forgetfullness" due to Covid, that spurred the media to make that discussion popular, and people with normal cognition would likely join into discussions with "me too". Think of how ME has been dismissed by people who think that feeling normally tired (and recovering by resting a bit) allows them to understand how ME feels.
I'm not arguing that Covid can't cause "brainfog and forgetfullness". I'm arguing that the article is about the popularity of complaining about "brainfog and forgetfullness". Brainfog is hard to quantify, but someone could do a proper quantitative study on short and long term memory among the general population, but it would be hard to prove an increase unless someone else had done that study long enough ago. So, it's hard to prove that there is an actual increase in cognitive problems. Counting complaints is easier, but doesn't necessarily mean anything about the actual thing being complained about.
