Law Professor Jonathan Turley comments:

"In reality, these pardons will not absolutely protect these individuals from being subpoenaed to give new testimony on prior claims. Lying in such interviews or hearings would constitute new criminal acts.

In the case of Fauci, some members such as Sen. Paul have suggested that he lied under oath repeatedly about his knowledge of gain-to-function work at the Wuhan lab. If called again, he would have to repeat or disavow the earlier testimony."

What Turley is suggesting here is that if Fauci repeats his earlier testimony, he would be subject to prosecution for perjury if the government can prove the case. New testimony would not be covered by the pardon. To take advantage of the pardon he’d need to admit that he lied earlier. That could prove problematic in civil cases or, conceivably, even in forfeiture proceedings.