Where should I start....this release should not exists.
Ideally the entire 4.9.9 "relocation" release was just intended to inform that the plugin moved to a new artifactId/groupId combination.

As outlined in #571 or https://issues.apache.org/jira/browse/MNG-7204 there seems to be a problem where Maven will not forward the correct settings when you use the old coordinates with the 4.9.9 version.
Since the 4.9.9 release contains relocation information it essentially became unusable triggering this "fix".
Please note that the plugin is still moving to it's new coordinates.
This 4.9.10 release is just a follow up to avoid any silent configuration issues being present somewhere....

TLDR:
If you can use:

<groupId>io.github.git-commit-id</groupId>
<artifactId>git-commit-id-maven-plugin</artifactId>
<version>5.0.0</version>