Update multiplexing threshold

Author: sketsdever

docs/flashbots-auction/advanced/gas-fee-refunds.md

@@ -34,7 +34,7 @@ The Flashbots block builder does not land 100% of blocks. In order to land bundl
 
 To share bundles with other builders, add the `builders` field to your `eth_sendBundle` request. The `builders` field accepts a list of strings which correspond to the "name" tags of [registered builders](https://github.com/flashbots/dowg/blob/main/builder-registrations.json).
 
-All `eth_sendBundle` requests are shared with the Flashbots builder. They are multiplexed to other block builders at the end of the slot (<= 0.5s before the slot ends) if the Flashbots builder determines it will not win that block.
+All `eth_sendBundle` requests are shared with the Flashbots builder. They are multiplexed to other block builders at the end of the slot (<= 1s before the slot ends) if the Flashbots builder determines it will not win that block.
 
 For example: