But it's still an effect of the treatment. If you perform a study on people whom have been ill you're going to get results that show all the symptoms of illness.. the study could have been done with any illness and likely show cognitive decline.
The point is that if you have a non-ICU covid case, this research is unlikely to apply.
The findings were concerning to anyone who had it, they also mention cases where the cognitive deficit was the first reported symptom.
Why do we have to make up extra rules for everything Covid-19 related?
Is it a symptom of the illness or a symptom of the treatment? If you had a better treatment protocol, would it still happen to the same degree?