Color of Roadsignes

Hello!

Is there actual a problem with the street-categorys? I mean the color of the road-signes that are displayed. They are ALWAYS blue, like the one on the Highway (german Autobahn), like this: https://de.wikipedia.org/wiki/Datei:Zeichen_332-20_-_Ausfahrt_von_der_Autobahn,_StVO_1992.svg

Wasnt they yellow/orange in the past for "lower-category-roads" (Bundesstraßen in Germany), like this: https://de.wikipedia.org/wiki/Datei:Zeichen_332-21_-_Ausfahrt_von_anderen_Straßen,_StVO_1992.svg ?

The voise also tells often "nehmen Sie die Abfahrt (Ausfahrt?)" (take exit...") in normal streets (Bundesstraßen).

Or do I mix up this with an older navigation-device, that I had? Were the street displayed signs always blue?