There is a tunnel inside a tunnel here (rail)

https://www.openstreetmap.org/way/1119628923

https://www.openstreetmap.org/way/975709366

The tunnel is signed on the pin and on the exit at Vivier d'Oie and it's not Tunnel du Vivier d'Oie ...

(spoted this week on L26 train)

Tunnel Bois de la Cambre - Tunnel Terkamerenbos (not sure if it's signed in 1 word or 2 word in nl Ter Kammerenbos)

So v1 of wikidata wast mostly correct until same user decide to change it ...

Unfurtunaly i haven't found picture of this signage, and you need to be lucky to catch all 2 signs as it's in fr in one side and in nl in other side (in each entrance) or doing AR beetween the 2 stations and making a video.

There is probably some cab view of l26 on internet to catch it.