So according to George Kent the Burisma investigations were terminated in early 2015 and someone likely bribed the prosecutor to close them.
Kinda throws a wrench into the whole "Joe Biden admitted that he bribed the Ukrainian President with $1 billion dollars to fire lead prosecutor investigating his corrupt son in 2018" theory.
The pervasive and long standing problem of corruption in Ukraine included exposure to a situation involving the energy company Burisma. The primary concern of the U.S. government since 2014 was Burismas owner Mykola Zlochevsky whose frozen assets abroad we had attempted to recover on Ukraines behalf. In early 2015, I raised questions with the deputy Prosecutor General about why the investigation of Mr. Zlochevsky had been terminated, based on our belief that prosecutors had accepted bribes to close the case.