If this outoor seating exist , it's a veranda completly closed and there's a gap between the wall on Rue d'Irlande and his structure.

It's a new structure not visible on aerial or in mappilary.

(spotted this morning).

From here it's also maxspeed 30 : https://www.mapillary.com/app/?pKey=194839143382325

But after pitch it's Vlanders and few meters again Brussels. Can somebody more experiment check and fix this ?

According to this webinaire of Sewer Museum this is a "bras mort" de la Senne.

https://www.youtube.com/watch?v=nuIE7tNdqOw (circa 20'20")

Check/research if a culvert realy exist here. (société intercommunale de la Senne for construction/ deviation) and Vivaqua if still exist. (not on hydria or Bruxelles environnement open data).

way/795912355 (petite Senne)

From ? until Crossing Albert/Mons : https://monument.heritage.brussels/fr/Anderlecht/Rue_des_Goujons/10700195 indicate that the river was dry up around 1950-1960

Per memory : Broekbeek under Rue du Collecteur that cross the way exist as culvert (circa 1890-1910)