Street items appearing in the household's inventory

When I was playing in San Myshuno with my sim, I got the notification you can see in the picture, which says “One or more objects that have been left on the street have been moved to your household inventory to make room for happenings on the open street.” I was confused because my sim left the house once and didn't have anything with her, so I opened the inventory. And the inventory had the street items, such as some lampposts and stalls. This is making me confused, does anyone know why could it be?