The present work investigates the evolution of the defect structures of a single crystalline multi-component CoNi-base superalloy. Shearing under stacking fault formation is favored compared to shearing by APB-coupled dislocation pairs with increasing plastic strain, at lower strain rates and at higher temperatures. This transition is associated with an anomalous increase in the yield strength and higher work-hardening rates. By using a novel approach to quantify the defect structures in combination with atomic-scale characterization, the share of each deformation mechanism is calculated. Thus, the anomalous behaviors are rationalized