I encountered a situation that made me doubt everything I know about Ethereum transactions.
In block 14721317 the transactions in positions [0, 1, 2, 3, 5, 9] all contain the same BuyOrder to buy the same NFT on OpenSea. Of course only one of them could go through, and the winner was the one in position #0.
Here comes the point: the TX in position #0 is the one with the lowest transaction fees among them! And not by little, but over 200 times smaller! I'll summarize here the gas paid by each TX here:
--- Start of block ---- Position #0: Base: 40.5 Gwei , Max: 333 Gwei , Max Priority: 5 Gwei , Gas limit: 277,845 | 203,986 (73.42%) , nonce: 3758, SUCCESS Position #1: Base: 40.5 Gwei , Max: 1115 Gwei , Max Priority: 1115 Gwei , Gas limit: 350,000 | 72,556 (20.73%) , nonce: 249, REVERT Position #2: Base: 40.5 Gwei , Max: 1500 Gwei , Max Priority: 500 Gwei , Gas limit: 505,000 | 72,496 (14.36%) , nonce: 387, REVERT Position #3: Base: 40.5 Gwei , Max: 777 Gwei , Max Priority: 444 Gwei , Gas limit: 505,000 | 72,496 (14.36%) , nonce: 1763, REVERT Position #4: Not a TX of interest Position #5: Base: 40.5 Gwei , Max: 407.8 Gwei, Max Priority: 279.6 Gwei , Gas limit: 234,650 | 72,104 (30.73%) , nonce: 0, REVERT [... not TXs of interest...] Position #9: Base: 40.5 Gwei , Max: 1200 Gwei , Max Priority: 250 Gwei , Gas limit: 255,615 | 72,556 (28.38%) , nonce: 2324, REVERT [...] --- End of block -----
By my humble knowledge, I was quite sure that the miner would have reordered these TX he just pulled from the mempool, in a way to maximize his tx fees, but here he clearly didn't.
I know that the way TXs are put in blocks is not a standard and each miner can decide how to do it by himself, but this behavior doesn't make economic sense.
Could it be a feature to avoid front-runners? i.e. TXs order is solely based on the received time-stamp? Tho I see it very unlikely that a miner operates for the world's good and not for his economical interest.
I already looked at this older post , where the only point that I see could apply is the following, but I think its highly unlikely - tho I'm running a blockchain analysis to rule that out.
Transactions that origin from the miner node will be put first.
What am I missing?