How to inject a specific (list of) molecule plugins with pipx

[JiElPe-Fr38]

I tried to inject the docker molecule plugin into a pipx installed ansible-dev-tools package with :
pipx inject ansible-dev-tools 'molecule-plugins[docker]
But, when checking with molecule drivers command, I saw that all drivers were installed, just as if pipx inject ansible-dev-tools molecule-plugins were executed.
Is it a bug or have I mispelled something ?