BUG #17536: PostgreSQL 10 initdb with locale de-x-icu fails on Windows Server 2012

The following bug has been logged on the website:

Bug reference:      17536
Logged by:          Stefan Hoffmann
Email address:      sh@rosesoft.de
PostgreSQL version: 10.20
Operating system:   Windows Server 2012 R2
Description:

Software:
Freshly installed Windows Server 2012 R2 (german)
Microsoft Visual C++ 2013 Redistributable (x86) - 12.0.40664.0
Microsoft Visual C++ 2015-2022 Redistributable (x86) - 14.31.31103
PostgreSQL 10.20 32-bit binaries from
https://www.enterprisedb.com/download-postgresql-binaries

Call (excerpt):
initdb.exe .. -E UTF8 --locale=de-x-icu --text-search-config=german ..

Error message:
initdb: ungültiger Locale-Name »de-x-icu«

According to  https://www.postgresql.org/download/windows/ PostgreSQL 10 is
supported by Windows Server 2012.
The collation 'de-x-icu' is contained in table „pg_collation“.
With default-locale "German_Germany.1252" initdb succeeds, but that locale
is not allowed in our environment!
On all newer Windows-OS (Windows Server 2016/2019/2022, Windows 10/11) there
is no problem.

Is this a PostgreSQL Bug?
Do you know a work-around?
Is a Windows-Patch or a special software necessary to use ICU?