Before the merge, there were some discussions on multi-block MEV.
Now that builders can just pay for their block to get included, the possibility of one entity being able to decide on the content of multiple blocks in a row increased significantly. Builder just have to pay enough and hope that the proposing validators are using mev-boost (which currently has a 50% probability).
Hey! This is indeed a problem, I haven’t thought through what being able to buy blocks for cheap means (aside from lowering cost of attack).
We have thought about multi-block MEV generally in the past, and the potential for the same entity to propose consecutive slots (this is a problem regardless of PBS). We briefly talked to the Uniswap & Euler teams about this and wrote a draft memo on what it means. I believe there were short-term band-aids possible where the oracle could be calculated over more slots but nothing convincing. I’ll ping them to answer here!
I’m currently analysing this a little closer and it looks like that certain flashbots builders (babe and dead) already had thousands of consecutive blocks.
That large validators can engage in something like that is one thing. But to me it looks like if everyday users are now able to do so by passing their blocks to the relays. It’s not even expensive.
I will post some updates as soon as they’re ready.