My only question is if this is violates the civil servant rules.
Far from it. Ambassadors are political appointees and serve at the pleasure of the President.
Vindman will still be paid by DOD as a LTC.
Sondland bought his job with a major donation so I guess he will just go back to being rich and bored. He was not civil service and served at the pleasure of the President, who had every right to be displeased.
If he wears the uniform, he isn’t Civil Service. He’s an officer in the DoD and perhaps past tense.
BTW, since nobody knows who the whistleblower is, POTUS could release the majority of personnel in the office and still not be guilty of violating the rights of any whistleblower.