The electrochemical CO₂ reduction reaction (CO2RR) is one of the key chemical transformations promoting the transition from fossil-based energy systems to renewable systems. Copper (Cu)-based materials uniquely catalyze the production of multi-carbon (C₂⁺) products from CO2. Yet, copper operational instability limits long-term performance. Herein, we investigate the impact of the chemical nature of the initial Cu surface, particularly oxidation state and carbonate formation, on the structural and operational stability of Cu catalysts along with their reconstruction kinetics. We combine state-of-the-art well-defined catalysts with quasi-operando electrochemical liquid-phase transmission electron microscopy (ec-LPTEM) along with electrochemical characterization to learn about underlying differences. We demonstrate that catalysts with higher initial oxide content undergo faster structural reconstruction and suffer from faster operational deactivation. Interestingly, we find that Cu carbonates further exacerbate the structural instability while also suppressing CO2RR activity. Our results highlight the critical role of oxides and carbonates in dictating the reconstruction pathways and durability of Cu under CO2RR conditions, offering insights into tuning Cu-based catalyst design for enhanced CO2RR stability and efficiency.