As explained above, validators on the Beacon Chain will need to run an execution layer client after The Merge in addition to their consensus layer clients. Pre-merge, this was strongly recommended, but some validators have outsourced these functions to third-party providers. This was possible because the only data required on the execution layer were updates to the deposit contract. Post-merge, validators must ensure that user transactions and state transitions blocks that they create and attest to are valid. To do this, each beacon node must be paired with an execution layer client. Note that multiple validators can still be paired to a single beacon node & execution layer client combo. This expands validators’ responsibilities but also gives a validator who proposes a block the right to its associated transaction priority fees (which currently go to miners).

https://blog.ethereum.org/2022/08/24/mainnet-merge-announcement/