retail CBDC is central bank money, so converting bank deposits into digital Euro changes the composition of the monetary base - fewer commercial bank reserves at the central bank, more central bank CBDC liabilities

ECB plans to limit the amount of digital Euro CBDC a wallet can hold

this means you will be limited the amount of digital EUR you can own

this applies only to retail European Central Bank CBDC, not wholesale. the idea is to prevent excessive outflows of deposits from banks