How Does a Block Builder Prevent Self-Front-Running?

A block builder prevents self-front-running by adhering to strict internal rules and, in some systems, by using Proposer-Builder Separation (PBS). In a PBS model, the block builder focuses solely on constructing the most profitable block and is separated from the validator who proposes it.

The builder is incentivized to include the highest-paying transaction bundles, regardless of who submitted them. If a builder attempts to front-run a profitable bundle they received, they risk losing the substantial fee from the original searcher, which may be greater than the profit from self-front-running.