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OSM Standard has no halo on secondary, while OSM-carto does have one in orange (see Castro street label).
Technically it's the other way around, but in any case the halo has been deliberately removed.
Miscoloured highway=secondary street name halos are one of the most common failures that I see during customization, so I won't be re-instating them. Motorway, trunk and primary have never had coloured halos.