Vitalik Buterin, co-founder of Ethereum, stated that the power of builders can be limited through partial block auctions to deal with their centralization risks. He mainly introduced two possible ways: Inclusion lists and Proposer Suffixes: In Inclusion Lists mode, proposers provide an inclusion list, and the list of transactions they require must be included in the block, unless the builder can completely fill the block with other transactions.
This design is fairly simple, but weaknesses include: incentive compatibility issues; additional burden on proposers. Builders can still engage in some abuse. Partial enshrining is required for account abstraction to work.
Another way to build it is to allow proposers to create a suffix for the block. The builder does not see information about the proposer’s intent when building the block, and the proposer is able to add any transactions the builder missed to the end. This approach reduces incentive compatibility issues, and while it may add an extra burden to the proposer, the proposer will get some MEV opportunity between getting a response from the builder and having to publish the block.
In any case, we need to minimise the burden imposed on proposers while minimising the power and information of builders, and this seems to be a clear indication that some third-party intervention is required in block production.