You are using the openmaptiles profile right? That would handled in the TransportationName class. If you want to change the handling you could fork https://github.com/openmaptiles/planetiler-openmaptiles, or if you think something would be generally useful to others you can suggest a change in https://github.com/openmaptiles/openmaptiles and it will get ported over to planetiler-openmaptiles.

This is the method that I now use to create PMtiles with planetiler

java -Xmx8g -XX:MaxHeapFreeRatio=60 -jar planetiler.jar osm_path=Osmfiles\netherlands.osm.pbf --bounds=world --water_polygons_path=data\sources\water-polygons-split-4326.zip --natural_earth_path=data\sources\natural_earth_vector.sqlite.zip --lake_centerlines_path=data\sources\lake_centerline.shp.zip --wikidata_cache=data\sources\wikidata_names.json --transportation-name-brunnel=true --tmpdir=data\tmp --temp_nodes=data\tmp\node.db --temp_multipolygons=data\tmp\multipolygon.db --temp_features=data\tmp\feature.db --tile_compression=gzip --output=9292NL.pmtiles --force

What I now see is that the transportation (Polygon) only have:

transportation (Polygon)
subclass platform
If there can be added the name or ref that should help me a lot