The first confident answer can quietly become the question everyone else is allowed to discuss.

Whoever speaks first with confidence sets the terrain. The rest of the group stops considering the question and starts considering the answer, arguing over its details, adjusting it slightly, treating it as the thing to be improved. That happens even when the first answer was a guess said firmly. Confidence gets read as information because it is available immediately and evidence is not.

If you speak first in a group, offer the question rather than your answer. If somebody else has, ask what other approaches were on the table before the discussion narrows any further.