A fact you can’t explain the source of is just a rumor you happen to believe.

A belief with no traceable origin behaves exactly like a belief with a good one, and that is the whole problem. You absorbed it from a video, a relative, a caption, and it now sits in your head with the confidence of something you checked. Not remembering where a fact came from is not neutral; it means you never weighed it.

Pick one thing you say with certainty and try to name where you learned it. If you cannot, spend five minutes looking for the source. Doing that a few times quietly changes what you repeat.