Found the study, which needs review and confirmation by other studies, but there have been many other indications that this is happening: https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(21)00084-5/fulltext
Here's CNN's:
https://www.cnn.com/2021/04/06/health/covid-neurological-psychological-lancet-wellness/index.html
As many as one in three people infected with Covid-19 have longer term mental health or neurological symptoms, researchers reported Tuesday.
They found 34% of Covid-19 survivors received a diagnosis for a neurological or psychological condition within six months of their infection, according to the study published Tuesday in the journal Lancet Psychiatry.
The most common diagnosis was anxiety, found in 17% of those treated for Covid-19, followed by mood disorders, found in 14% of patients.
And while the neurological effects are more severe in hospitalized patients, they are still common in those who were only treated in an outpatient setting, the researchers note.
I'm guessing that "most common" may be most common mental effects. Our DIL still has smell and taste deficits/alterations a couple of months later, and we know that neurological problem is a pretty common effect.