IPv6-Payload patch was removed with version bump in #383537 probably caused by a not cleanly matching patch from 2.2.0. It should be re-added with useflag ipv6 Reproducible: Always
Created attachment 303391 [details, diff] openvpn-2.2.2.ebuild.ipv6.patch patch for ebuild
Created attachment 303393 [details, diff] openvpn-2.2.2-ipv6-payload.patch adapted ipv6-payload patch
I'm not going there. Maintenance is a PITA; you should just wait for 2.3.