@roberto-bayardo feel free to add more details to this and edit it how you like, as the future owner for it.
What I got from our conversation about it is:
"the main op-reth changes for Holocene will be:

• (1) the 1559 parameter customization (incl. effects on tx-pool) and
• (2) the block-sealing will set the withdrawal-root by retrieving a storage-root of the withdrawals