Thanks for this!

OK for me to tag it with public_transport:version=2 yet? (if you're hands-off…)

Reason: I have a saved query for spotting old routes in need of modernising: https://overpass-turbo.eu/s/1KiC , and it's pinging on these.

Also, once they're tagged with the appropriate version, GeoFabrik OSM Inspector can see them, and that tool can highlight severed routes (top-left dropdown, Public Transport - Routes)