To answer this quest, one must consider how someone in a wheelchair will "feel" the situation.  We use "flush" kerbs when it is completely flat with no bump (or a very tiny bump), and "lowered" where an effort has been made to lower it but with still a bump or where the user must push to lift the wheel.  More than 90% of kerbs in Brussels are in the "lowered" category.
Finally, "raised" is when there is a huge step; sidewalks in Brussels are about 8-10 cm high, which is quite difficult for users in wheelchairs.

It’s good to ask this question.  Next time, please don’t take the picture top-down but from an angle, so that we have a better view of the step here.  I found a more recent picture in our Mapillary footage to double check this.

Fixed, thanks.