It’s not just big tech that’s getting the antitrust treatment from the Department of Justice. Late Monday afternoon, the Department of Justice tipped its hand that it was investigating Visa’s proposed $5.3 billion acquisition of the venture-backed Plaid, which allows applications to connect with a users’ bank account. It’s a tool that powers a good chunk of new fintech offerings, and the Justice Department has apparently spent the past year looking into how the deal would affect the broader market for new financial services coming from startups. Visa is acquiring…