throwaway
n. countablen. a comment or message that you post online because you know it will be ignored or deleted. You use this when you want to say something but don't want to be held responsible for it.
n. a statement or post made on the internet with the expectation that it will be disregarded, ignored, or deleted. Often used to express a controversial opinion without the intention of engaging in a serious debate.
He made a throwaway comment about the movie and then left the site.
The user posted a throwaway comment on the forum to avoid being doxxed by the other participants.
While the main thread of the discussion focused on policy reform, the throwaway remarks in the comments section revealed a significant amount of underlying frustration with the current administration.