The following bug has been logged on the website:
Bug reference: 16270
Logged by: Christian Wetzel
Email address: christian(dot)wetzel(at)gmail(dot)com
PostgreSQL version: 12.2
Operating system: SLES12
Description:
https://download.postgresql.org/pub/repos/zypp/repo/pgdg-sles-12.repo
contains the URL as
https://download.postgresql.org/pub/repos/zypp/12/suse/sles-$releasever-$basearch
which is converted to
https://download.postgresql.org/pub/repos/zypp/12/suse/sles-12.5-x86_64
while the correct URL is
https://download.postgresql.org/pub/repos/zypp/12/suse/sles-12-5.x86_64
(dot and - switchted)