Hello.

I suggest you inspect OSM data more carefully before dropping comments like this.

The reason for the merge is that UrbIS considers this to be a single building structure with a single ref:UrbIS number.

I agree that this structure is made of several parts, and that is why it was designed while respecting the existing shapes of the 3 parts, which can be found here.
https://www.openstreetmap.org/way/23216348
https://www.openstreetmap.org/way/23216362
https://www.openstreetmap.org/way/1013595845

No strong opinion myself about VauxHall.  I have been there a few times, it is indeed a covered structure, it may qualify as a roof if you prefer.  I’ve just made the change.