a CBDC has advantages over normal digital fiat.
You can't compare those two, they are apple and oranges even if that sounds strange.
Central bank digital currencies are going to replace cash, they won't be an alternative to a digitally represented fiat. A transaction that is done via your bank is an IOU-based. CBDCs won't have any difference from cash other than humiliatingly bad privacy. So, it should be properer to say that CBDCs have disadvantages over, say Bitcoin.
obviously it has many many many disadvantages over bitcoin. i listed a few..
but governments are trying to go "cashless" meaning its not going to be a digital cash + CBDC its just going to be CBDC
but like i also said if it went full 'bank authorised' both in registration and payment sign off. then all 'cash' features are gone. which is the negatives of CBDC
there would need to be a way for people to make their own independent keys with no banker multisig to retain
some "cash" features