I know it's wrong. Why does reporting it still terrify me?

You and your team already know. You've said it to each other in private, more than once, maybe in careful words. No one disagrees about the wrong. And still, no one has said it to the people who could do something about it. Here is what you are avoiding: waiting for the fear to pass is not a plan. It is comfort wearing the mask of caution. The risk is real — blame, isolation, cost to your position. No one will tell you otherwise, and you should not tell yourself otherwise either. But look at what is actually in your hands. You control the account you write, the facts you gather together, the order you speak in, and who stands beside you. You do not control how it is received. Decide, right now, which part belongs to you — and if the stakes involve real danger or retaliation, bring in someone outside your team who knows the formal channels before you act alone.