So I gather you are not talking about layer properties
described on this webpage:
https://docs.qgis.org/testing/en/docs/user_manual/working_with_vector/vector_properties.html
Can you find what you are talking about in the help files?
Or maybe record a short desktop session with Kazam on Linux
o
I got a problem with layers that are displayed in the layer design
dialog ("Layergestaltung" in German) but not in the layer window itself.
I would like to delete these layers but this is not possible. I opened
the project in QGIS 2.18 and in 3.10 and it happens in both versions.
Can anybody he