The first Trump presidency is known for the longest government shutdown in US history.
Job stability is not a given for federal employment anymore.
Other than that, I would say non-defense jobs are certainly worth maintaining institutional knowledge.
I would not be surprised if this was repealed (if only as an effort to further purge government employees):
https://en.m.wikipedia.org/wiki/Government_Employee_Fair_Treatment_Act_of_2019
Prior to this, my understanding is that back pay was given in good faith, not by actual requirements.