No, I think the other commenter is right. They definitely store every version of every comment on their backend. Just because it's not displayed publicly doesn't mean they don't have the data.

That literally means nothing at all on their server backup from the year before. You could delete and rewrite your comments a thousand times and it would do you the same amount as good as one time, and barely any better than doing it no times at all. Your entire 15 year comment history would take up probably 10MB of space at best. They'll have several back ups taken over the last decade. They aren't just going to be selling off the live servers info.

I imagine that they would. Text is trivially easy to store, and storing multiple versions would let them catch users who might edit away rule breaking they posted to avoid bans, but it's probably one of those internal tools.

From a data handling perspective, it'd be more efficient to handle edits by having a common id field, and an additional version/edit counter that increments --adding the edit like its a normal post-- , than it would be to edit data the usual way, since you don't have to go back over the whole database to find the comment, or worry about it falling out of sync if one copy of the database has the edit, and the other has the original.

You'd just need to fetch the comment by id, and the database entry with the highest version count to display it, which would be fairly easy to do.

if you request your data from them under CCPA, and it shows the edited comments as gibberish, you're good. I did the same thing but I left the comments to simmer for a long time like months.