Take the L and move on. You made a reasonable mistake (it’s an old phrase that not many people recognised, iirc), learn from it and let it go.

Honestly just an edit in the post saying you didn’t know the phrase’s origin would have been enough. No need to make it into a “thing”. That’s probably where the downvotes are coming from.

Part of being a good person is realising and accepting that people make mistakes. Anyone that still keeps giving you crap over this after you’ve apologised probably isn’t worth listening to.