The European Central Bank and EU national central banks have opposed a proposal requiring major stablecoin issuers to hold at least 60% of reserves as bank deposits under MiCA regulations. The central banks argue this mandate could expose banks to stablecoin market volatility and undermine deposit stability, recommending instead that a portion of reserves be held in short-term assets maturing within one to five business days. Despite MiCA's implementation, the ECB warned that non-compliant crypto firms can still access EU customers, creating significant enforcement challenges and investor protection risks. The central bank system emphasized that current regulatory execution gaps pose threats to market integrity as the framework continues to evolve.