The phrase "disproportionate influence" means having an impact or control that is greater than what would be considered fair or appropriate in a given situation. Full definition
He cites the group's disproportionate influence on technology, social media, fashion and other sectors. (entrepreneur.com)
This is especially the case when, for reasons of law or practicality, corporations have disproportionate influence in shaping global agreements. (larrysummers.com)
Trade union leaders remain under fire for exercising disproportionate influence over Labour: not all of their members vote Labour, but their numbers count in shaping policy and pre-selections. (theconversation.com)