The other risk is referred to as structural disintermediation: bank customers could shift a significant proportion of their bank deposits from their current or other deposit accounts to CBDC (Central Bank Digital Currency). For commercial banks, this would mean losing a cheap and stable source of funding.
Depending on the market situation, banks can use overnight deposits to obtain funding for a few basis points less than from other sources, such as refinancing operations with the central bank or bond issuance.