I was only trying to offer you a fig leaf as it's abundantly obvious that the current law is fine. After all, if the current law was a problem the last century or so should have shown us that. If anything it shows the opposite. I'm going to go with demonstrated factual experience over hypothetical concerns.
This is especially important because Congress having access to the President's financial information is absolutely vital to both national security and the function of government. If you haven't been concerned over the last two years about the fact that we as a country would have literally no idea if a hostile foreign government were bribing the president I can only shake my head in amazement.
Sorry that's unconstitutional and no law can change that. Their immunity is absolute from both criminal and civil law while engaging in debate and legislative activity. This is an extremely important protection for the legislature as it protects Congress from the armed police forces of a hostile president or hostile civil actions from citizens.
https://fas.org/sgp/crs/misc/R45043.pdf