> So why there 2.3 version is in beowulf while buster's package is 2.4?

FWIU, it seems this package is compiled from Devuan's CI and not merely
merged from upstream: https://ci.devuan.org/job/openvpn-binaries/

I have no idea about what kind of problem made that package not having
been recompiled since 3y 8m. I guess only a dev could shed some light on
the underlying reasons?

Bernard Rosset
https://rosset.net/