www.F4map.org is puzzled? I was checking my new project with it and got odd renderings. in #F4Map there is an option "F4 specific buildings" to show GLB files instead of OSM tagging 3D buildings. But in the case of #Westmister, there is no GLB available, the OSM tagging is quite good. Only in F4 the rendere seems to freak out. You often see a good rendering. (My tool seems to have wrong wall colours) Often you see only parts of the 3D area.
Some of the #OSM tagging is not well defined in all details. So I indented to always check F4, what it does to mimic it. But well, software is never free of errors.