It's not so easy when you feel like you can't trust the people to whom you report. I'm in this situation after attempting to be candid about what I felt were missteps on the part of my manager and a director of engineering. After a scolding from one of them, and a veiled threat about my employment ending, I now feel like I just shouldn't rock the boat. I mostly dread my 1:1s with them, and I don't feel like those meetings are time well spent.
I could maybe understand if I had offered unsolicited feedback, but they asked for my opinion and I gave it honestly.