In the era of decentralization, shared leadership has garnered significant acclaim. However, when multiple leaders coexist within a team, the phenomenon akin to “too many cooks spoil the broth” will occur. Given the lack of research regarding the darker aspects of shared leadership, this study investigates the contingency mechanisms of shared leadership damaging team performance. Based on team power conflict theory, we predict that in high leadership distribution disparity or team external environment complexity, shared leadership will induce factionalism within the team member exchange network (TMX) and further impair team performance. In a sample of 90 knowledge-based teams in China, we find that the TMX network EI index partially mediates the relationship between shared leadership and team performance. The leadership distribution disparity and environment complexity moderate the mediating effect of the TMX network EI index. This study contributes to a deeper understanding of why and when shared leadership impairs team performance and offers insights into alleviating the adverse effects of shared leadership.