Well, I can tell you that both website's didn't update yet their network.
Cycleroute 80-81 is signposted via Drève de Boondael. Here's the proof -> https://www.mapillary.com/app/?pKey=796548715388721
Can I therefore ask you to revert your changeset?
For your info, I was involved 3 years ago in establishing the cycle node network in Brussels. 
In 2022 the Brussels region decided to modify/update and signpost the network.
Compared to the original network, they did here a modification. I am not very happy with it, but as long as the signs are how they are, we need to map according to the ground truth principle ...