There is a new pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages xpra
https://github.com/void-linux/void-packages/pull/18770

xpra: create "xpra" system group on install
Xpra installs a udev rule that relies on the existence of an "xpra" system group. This group should be created when the package is installed.

A patch file from https://github.com/void-linux/void-packages/pull/18770.patch is attached