Updated, thanks.
https://www.openstreetmap.org/changeset/148877044

Aerial imagery of the part outside of the tunnel shows they repainted to have only one lane.

Fun fact: I was trying to see if we have Mapillary imagery of this tunnel—because most pics in Brussels are taken by people on bicycles 😉—and found this one from 2021:
https://www.mapillary.com/app/?pKey=255785303171283