It was not known what she had done as the Ukrainians could not get anything through the State Dept.
Rudy Giuliani was acting as the President’s defense attorney during the Russian-Collusion witch hunt with Mueller trying to get dirt on POTUS via Manafort and Manafort’s contacts in Ukraine.
Giuliani traveled in Ukraine in 2018 to gather evidence that the President was innocent. When he went there and started making inquiries the Ukrainians informed him they had been trying for more than a year too get evidence of corruption on the part of US officials (Biden and others) to the US Govt and were stopped by Yovanovich.
One of the biggest challenges for POTUS is finding qualified and experienced people in and out of government to fill key positions. Likely, there were persons (deep state, resistance, remember Sally Yates?) in the chain that influenced hiring and retention. Yovanovich was likely protected until Rudy confirmed she was bad news.
Why would PDJT have to have Gulliani confirm that someone was bad. They were part of the HRC machine in the state department and should have been given their walking papers the FIRST effin year of his term.