Blocks `base_fee_per_gas` don't match EIP-1559

[anaPerezGhiglia]

Problem description

While developing NomicFoundation/edr, we identified at least six blocks on Base Mainnet whose header base_fee_per_gas values do not match the values derived from the EIP-1559 calculation. We were unable to find any specification or documented exception that would explain this discrepancy.

Technical details

• All failing bocks are blocks which parent gas used was over the target
• The inconsistent blocks are:
  • 39628092
  • 39628093
  • 39628094
  • 39628095
  • 39628096
  • 39628097
• Other over-target blocks do match EIP-1559 specification.

You can check the tests that evidence this here

having ALCHEMY_URL environment variable defined in context you can run the tests with

cargo test --package edr_op --test main --all-features -- integration::base_fee_calc::test_dynamic_base_fee_base_mainnet

Double checks

We have validated that:

• the data returned by Alchemy json rpc node matches the data exposed by basescan
• EDR base fee calculation matches the EIP-1559 spec
  • in the tests we are also validating that EDR calculations matches alloy-eips calculation to double check.

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Note: Sorry in advance if this issue does not belong in this repository.