It’s not about tax returns. It’s about laundering and that $10,000 trigger.
The treasury likely has bank records scarfed up by Presidential Envoy Rudy on of his anti corruption fact finding missions to ukraine. Do not be bamboozld by the misdirection of American evidence. There likely is none.
The real damning evidence was in Ukraine until Rudy brought it home
The corrupt Americans are no longer protected by the Ukranian government