For example, the proposed design gives the winning builder a headstart in knowing what the next state of the chain will be and an incentive to delay revelation of that state as long as possible. This constitutes a research direction in itself.
I’ve been thinking about this exact issue in the back of my mind for a while. This isn’t the most pressing problem with ePBS, but it is interesting nonetheless. It is not only a problem with Ethereum’s PTC proposal, but also with ePBS designs for layer 2s and other layer 1s that use different kinds of consensus/sequencing protocols (such as optimistically responsive or DAG protocols). I don’t have definitive answers, but I wrote some preliminary thoughts here: