Everything was fine, except for one detail: I booked a single room for my friend, with a balcony, and it was confirmed by MooStay. However, when checking in at 18:00, MoonStay staff arranged for a room with only a window to look out onto the street, with the reason: the balcony room was already occupied by another guest (???). And as I understand it, the price of a room with a balcony is higher than the price of a room without a balcony, and MoonStay did not mention refunding the difference.
In addition to the above detail, MoonStay is very conveniently located for resting and waiting to go to the airport. The room is clean, quite quiet. There are many shops and food around. You can walk to T1 terminal.