The phrase "untapped potential" means having the capacity or ability to achieve more, but it has not been fully utilized or explored yet. Full definition
«However, even these higher expectations remain modest compared with the huge untapped potential of renewables. (iea.org)
Given the large variety of super abilities and weapons that you have, there was a lot of untapped potential for open world activities to take advantage of each one. (playstationlifestyle.net)
Chris Coleman still sees a lot of untapped potential in Callum McManaman and has backed the Sunderland winger to prove his worth for the club. (si.com)