This is not exactly a logo on a bedsheet. And what do we call these things
that blur the distinction between banners, bunting and billboards?
There
are several reasons for questioning the authority and flaggishness of this item:
Swiss Post Solutions seems to be a subsidiary company of Swiss
Post, and the website illustrating and hosting this "flag" is Dutch, not
Swiss.
English is not one of the official languages of Switzerland.
There have been no sightings of this "flag" rendering the logo in any of
the four official languages of Switzerland.
Switzerland is a very flag-conscious country, and strangely-shaped
banners are almost always clear derivatives of official flags. In this
instance, there appears to be no such flag.
The Swiss PTT, formed in
1920, was broken up in 1998 to form La Poste (Die Post, La Posta) and
Swisscom. PTT also does not appear to have ever had a flag. T.F.
Mills, 15 August 2019