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

xbps-src: don't export CCACHE_COMPRESS=1
https://github.com/void-linux/void-packages/pull/38986

Description:
ccache enables compression by default since version 4.0.
This variable is redundant and prevents disabling compression through
a config file (useful e.g. on compressed filesystems).


AFAIK there's no way to disable compression when `CCACHE_COMPRESS` is present, since the environment has the highest precedence, according to the manual:

```
The priorities of configuration options are as follows (where 1 is highest):

 1. Environment variables.

 2. The primary (cache-specific) configuration file (see below).

 3. The secondary (system-wide read-only) configuration file
     <sysconfdir>/ccache.conf (typically /etc/ccache.conf or
     /usr/local/etc/ccache.conf).

 5. Compile-time defaults.
```

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