This is a good issue to raise on a continuous basis. The problems here never fully go away because the tensions here are ongoing and the spirit of openness required must be reinvigorated on a regular basis.
In my earlier professional life I spent 25 years as a public sector labor union rep. I was involved in dozens of whistleblower cases and followed hundreds of others.
Management attitude and agency culture are a big part of the equation, but can often turn on a dime when new political appointees come in to head agencies.
I urge institutional protections: collective bargaining agreement provisions, statutory protections (including hefty sanctions against those who try to enforce cultures of silence), and civil service code provisions.