When you tab to the filter options and then hit enter you open the area with the filters. The expected behaviour is that you can then select your filters. But before you can do that you have to navigate past the sort options.
It is true that this is not any extra keystrokes compared to the current dropdown filter select but it is not a logical order. A screen reader would also be confused by this.
The order of the tabulation must be logical, in accordance with the source order and visual order.
New template

Old template

First reported joomla/backend-template#310 26 June