Deep Dive on Polygon zkEVM and zkSync Era Wallet Populations

Recall from the zkSync Era Bridge tab that there is a discrepancy between Flipside and Etherscan of ~26 ETH on 2023-07-22. This is a deep dive into the reason for the discrepancy. Short version: The difference is due to fees paid for bridging tokens (USDC for example) for ETH bridged in via third-party bridges. There is no data issue on either Flipside or Dune. Both are correctly showing direct user wallet interactions with the official zkSync Era Bridge, but the fees and third-party bridge-ins need to be accounted for separately using internal transactions.