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

https://github.com/zdtcd/void-packages firefox-esr
https://github.com/void-linux/void-packages/pull/14229

Firefox esr
Built and tested for:
- x86_64

Building in progress for:
- x86_64-musl

A patch file from https://github.com/void-linux/void-packages/pull/14229.patch is attached