Here is what AG Barr may be investigating:

Real Clear Investigations:
Attorney General William Barr shocked official Washington Wednesday by saying what previously couldn’t be said: That the counterintelligence investigation into the Trump campaign in 2016 involved “spying.”
The spying, which Barr vowed to investigate, is not the only significant possible violation of investigative rules and ethics committed by agents, lawyers, managers, and officials at the FBI and the Department of Justice. A catalogue of those abuses can be found in recently released testimony that Edward William Priestap provided to Congress in a closed-door interview last summer. From the end of 2015 to the end of 2018 Bill Priestap was assistant director of the FBI’s Counterintelligence Division, which meant he oversaw the FBI’s global counterintelligence effort.

In that role, he managed both of the bureau’s most politically sensitive investigations: the inquiry into Hillary Clinton’s handling of classified information and the probe into whether Donald Trump or his campaign conspired with Russia to steal the 2016 presidential election. His testimony provides rare insight into the attitudes and thoughts of officials who launched the Russia probe and the probe of Special Counsel Robert Mueller, whose final report is expected to be released very soon.
More important, his testimony contains extensive indications of wrongdoing, including that the FBI and DoJ targeted Trump and did so with information it made no effort to verify. It paints a portrait of the Obama-era bureau as one that was unconcerned with political interference in investigations and was willing to enlist the help of close foreign allies to bring down its target. And, perhaps presaging a defense to Barr’s claim that American officials had spied on the Trump campaign, it showcases the euphemisms that can be used to disguise “spying.”