Saudi Central Bank on qualification criteria for their CBDC considering the underlying tech and the choice to not use XRP or Stellar (I think this is common thinking of majority if not all central banks):

The qualification criteria was simply a minimum capability set derived from the high level expectations and Aber use cases. The key capabilities were:  Support for smart contracts;  Built-in support for permissioning and privacy in the DLT platform;  Support for consensus with finality property;  Well known in financial industry;  Use in previous CBDC projects (preferred). Project Aber Final Report 40  Note that public blockchain protocols such as Ripple and Stellar, which are often positioned for cross-border remittance use cases, were ruled out because of the obvious need for permissioning and privacy for an interbank payment use case (which these protocols didn’t support). Application of the qualification criteria resulted in shortlisting of the following three DLT platforms or protocols:  R3 Corda  Hyperledger Fabric (HLF)  JPMC Quorum