There's a closed pull request on the void-packages repository

Make python3 default in XBPS environment and hooks
https://github.com/void-linux/void-packages/pull/21132

Description:
The `03-rewrite-python-shebang.sh` hook assumes `python2` by default, overriding only if `python_version` or `pycompile_version` are set, or the package installs some modules in `/usr/lib/python*`.

Not all packages that install Python scripts set these variables or install modules, so the shebang is forced to `python2` by default. Because `python2` is EOL, I think it is sensible to assume these packages are doing the right thing and targeting `python3` instead.