Yes, all addresses within "1000 Brussels" were broken after our friend created a new suburb on the map.
https://www.openstreetmap.org/node/10760617336/history

Nominatim suggests the nearest postcode area (https://www.openstreetmap.org/way/1025277910), but would also return 1050 1060 1070 1080 or 1210.

Queries on ordinary addresses should work fine now.  Named POI are cached and may need another 24 hours to return the correct value.