Description:
In the current design of MEV-Boost, relays release (header,bid) pairs to all instances of mev-boost that pings it (please correct me if this is wrong). This means the pairs are public information that can be used as input for auction participants.

For example, a builder could watch the 'mempool' of (header,bid) pairs, see what the maximum bid and compare it to the maximum they're willing to bid. If they can bid higher than max_current_bid then they just add 1 wei to it.

If you assume this behaviour from multiple builders, we have a game where:

• the optimal bidding strategy is to bid by increments and always bid the smallest increment allowed more than the current 'winning' builder.
• the optimal bidding strategy is to wait until the last possible moment to bid as to not reveal the information to other bidders.

Questions:

1. Should we make the 'mempool' private only to the proposer of a slot? Technically this would require proposers to send an authenticated message to the relays, proving that they are the proposers of the current slot. How technically difficult is this?
2. Is this PGA behaviour problematic? Does it overwhelm the communication network or pollute its bandwidth with incremental bids from builders or burst of bids close to the deadline?
3. What does this non-sealed bid auction look like?
4. Is this a worry at all since in a repeated game, this should trend towards bidding max of the opportunity?