Did you see the green bar in the picture? It is just below the header.
These 2 columns have different green bars. One is a complete green bar while the other is shared with a grey bar. The green bar is an indication that the list in that column.
If the green bar is full, it means that all the values are displayed.
But if the green bar is shared with a grey bar, this means that some of the values are filtered.
Actually, there is another colour. It’s red. When it appears, it means that the column contains error values.