Hope the following information from pacemaker upstream maintainer is clear
enough to describe the issue:

```
Pacemaker uses both the standard C regex API and the ncurses API.

Tumbleweed now builds ncurses using --with-pcre2 to use libpcre2-posix
as a drop-in replacement for the standard API. Pacemaker inherits
linking against the pcre2 library when built with this ncurses.

However, code using pcre2 must include pcre2posix.h instead of regex.h
(unless pcre2 has been installed as regex.h, which it has not in
tumbleweed). Pacemaker includes regex.h, which defines various
constants (e.g. REG_NOMATCH) differently from pcre2posix.h, wreaking
havoc.

Any package using both regex.h and ncurses will be in the same boat.
```