Federal non-prosecution agreements in the US only are effective concerning specifically defined and specifically enumerated charges.Generally there wopuod be no blanket immunity.
She can be charged with a crime not covered by the agreement.
Such an agreement is often made in exchange for turning state’s evidence. She may have changed her mind about providing such evidence, or maybe the DOJ changed its mind.
We will know next Tuesday what the charges are. I expect it will never go to trial because of the risk of jeopardy against certain individuals protected by the Deep State, such as the Clintons. She was likely extradited to the US to make sure she shuts up IMHO, unless AG Barr is riding herd on the case, and he has not even mentioned it publicly except to excoriate the Dept. of corrections in Epstein’s death.
Lady Body Language thought it was significant that they didn’t show a mug shot at the press conference announcing the arrest.