Another mapped changed it into highway=footway yesterday after reading the story in the newspaper.

I have no strong opinion about whether highway=footway, =cycleway, =service or even =pedestrian would be the most appropriate.

Authorities in Brussels are closing more and more streets to traffic, and without any traffic signs it is doubtful what is their legal status, e.g. motorcycles are technically able to bypass the barrier but they were probably not intended.

(Other example here, I am not sure whether I made the right choice: https://www.openstreetmap.org/way/581918263/history)