Baker McKenzie flagged a structural problem with 1099-DA last week: broker gross-proceeds reporting does not reflect actual cost-basis reality for DeFi users. The result is phantom income risk, basis gaps, and forms that are technically compliant but operationally misleading. The market is no longer asking "what is 1099-DA?" It is asking "how do we fix the forms we received?" That is a different problem. It requires reconstruction, not just reporting.