Quote from https://bitcoinops.org/en/topics/anchor-outputs:
As of this writing, the most recent versions of the design add two outputs to the commitment transaction—one for each LN party—and require all other outputs in the commitment transaction to have their scripts encumbered by a
1 OP_CHECKSEQUENCEVERIFY (CSV)condition that prevents them from being spent for at least one block.
As far as I understand https://github.com/lightningnetwork/lightning-rfc/blob/master/03-transactions.md#offered-htlc-outputs , the addition of
1 OP_CHECKSEQUENCEVERIFY (CSV) is the only thing that changes within the output scripts of the Bitcoin transactions used by the Lightning protocol.
But why is this necessary? Why can't we just use CPFP without that relative delay of 1 block?