Let’s pretend for a moment that we know that Reddit has any sort of decent versioning system, and that it keeps the old versions of your comments alongside the newer ones, and that it’s feeding the LLM with the old version. (Does it? I have my doubts, given that Reddit Inc. isn’t exactly competent.)

They almost certainly do, if only because of the practicalities of adding a new comment, then having that be fetched in place of the old one, compared to making and propagating an edit across all their databases. With exceptions, it’d be a bit easier to implement it as an additional comment, and increment a version number that you fetch the latest version of, rather than needing to scan through the entire database to make changes.

It would also help with any administration/moderation tasks if they could see whether people posted rule-breaking content and then tried to hide it behind edits.

That said, one of the many Spez controversies did show that they are capable of making actual edits on the back end if they wished.