Downsides of CBF

With bloom filters, SPV clients can subscribe to a full node to receive transactions containing a particular address. This has the advantage that those full nodes can provide transactions already when they enter their mempool and even before the transaction is included in a block. A wallet using bloom filters can see transactions earlier.

With CBF, however, the wallet needs to wait until a transaction is in a block since a full node can only create filters of existing blocks. The consequence is that unconfirmed transactions are not displayed in the wallet. Proponents of CBF argue that unconfirmed transactions are not trustworthy anyway and should not be displayed since they can lead to false information.

Another downside of CBF is that it has higher bandwidth requirements than bloom filters and address-indexed servers (like Electrum).