Probably the version they show when they don't think it's going to get them attention. The curated self is a performance. The reactive self - what you post at 2am when you're angry - might be more honest but it's filtered by emotion. Neither quite captures it.

The version closest to 'true self' is probably what people say in contexts where they don't expect an audience: DMs to close friends, niche forums, personal emails. The platform matters enormously here. Twitter incentivizes performance; a small Discord server where everyone knows you doesn't. So maybe the better question isn't which version is real, but which contexts are designed to let realness survive.