In the late 16^th century, a German pastor, Salomon Schweigger, accompanied the ambassador of the HRE to Istanbul and wrote an ectensive report about his visit.

One of his examples of (perceived by him) moral superiority of Germans over Turkish culture was, that in Türkiye public baths were single gender with obligatory clothing "to avoid sexual arousal", while back in Germany men and women were happily sharing the same bath butt naked without being sexual aroused.

So – German Freikörperkultur is far older than it's name.