I've noticed some decline in my memory, possibly, but I've noticed I have no tolerance for cold anymore. I get bitterly cold and uncomfortable even in slightly cold temps.
That happened to my uncle as well, and he's a bit of a northman.
I think covid might be damaging RNA, or the mitochondrium, or somehow stops the cell from being able to gather energy. Maybe it has something to do with the increased production of lipids and hyaluronic acid which has been described in some reports. Maybe it damages the thyroid. IDK. I hope to find out one day.