Does anyone else find this curious?

https://www.cbsnews.com/news/kirstjen-nielsen-resigning-dhs-secretary-expected-to-offer-resignation-today-live-updates-2019-04-07/

Nielsen's departure also means acting heads will soon be running DHS, the Pentagon and the U.S. Department of the Interior.

Acting heads (non nominated positions) now include:

Department of Homeland Security

The Department of Defense

US Department of the Interior

All of the aforementioned people were Trump nominations. They all received confirmations through congress. They all did things that Trump really supported, then left in a “personal spite or disagreement” with the president. All of them replaced with Trump picked “acting” heads.

Very curious to me.