TOP PRIORITY: CHECK WITH RESTAURANTS.
Dad has hearing issues and hearing aids. Sometimes his hearing problems get in the way of understanding what is happening. The hearing aids are not perfect as they do not address a tinnitus issue he apparently also has, and they are due for adjustment. But, they are in his apartment and there are extra batteries there for them in case the batteries have worn out.
He has always suffered from some form of anxiety/claustrophobia, which he controls via techniques including knowing what his plans were for each day. When he does not have information on plans or changes, and they simply happen without warning or explanation, he becomes disoriented. He is at the same time a relaxed and flexible person by temperament, and can maintain that attitude when he has information about what is happening, and (ideally) some input on plans.
He has also always had a touch of aphasia, never obvious because he is so strong linguistically and intellectually. It is of course now more pronounced; it is also exacerbated by anxiety. Knowing that his mind is clear behind the aphasia makes it easier to communicate with him.
On other cognitive issues: I know they are real but I strongly suspect that at least part of the problem is hearing and anxiety. I am not surprised that he is unsure of the date, given that he is not receiving his newspaper or the mail, and has been separated from his calendar. I hope he is not being treated as a person unable to understand most things, because he is not that.