The idea you kept to yourself in the meeting is the one someone else says out loud ten minutes later.

The reason you did not say it was probably that it seemed obvious, and obvious is what useful ideas feel like from the inside. Then someone else says the same thing and gets the credit, plus the reputation for being the person who contributes. What stops you is rarely the idea, it is the half second of exposure between thinking and speaking.

Say the first version of yours next time instead of the polished one. Even a question counts, and it puts you in the conversation early.