take the lid off (something)
To expose some secret to the public, often something scandalous, unpleasant, or deceptive. That company's stock price plummeted after the media took the lid off the CEO's embezzlement scandal.
take the lid off (of) something
and take the lid off 1. Lit. to remove the lid from something. (Of is usually retained before pronouns.) I took the lid off the box and set it aside. Karen took off the lid.
2. Fig. to reveal a set of previously concealed problems. (Of is usually retained before pronouns.) You took the lid off this mess. You straighten it out! You took off the lid, so you have to settle it.
take (or lift) the lid off (or lift the lid on)
reveal unwelcome secrets about. informal