Just updated Mantra to 3.0.5 and social media icons are now colourless.
(and margins and extra spaces everywhere, but that’s already in a separate topic).
Not happy.
We have expanded the social icons list in the version 3 release and these icon images look differently (lighter, smaller and uniform).
If you are not satisfied with the new look, you can choose to revert to an older theme release using the WP Rollback plugin or customize the social icon images used.