I opened some issues:

https://github.com/vmarc/knooppuntnet/issues/397

https://josm.openstreetmap.de/ticket/23587 (this outright framed as bug report as it is a bug)

https://github.com/osmandapp/OsmAnd/issues/19427 (this outright framed as bug report as it is a bug)

https://github.com/SomeoneElseOSM/SomeoneElse-style/issues/21

I also contacted wanderreitkarte via email.