Reddit recently removed years of chat and message archives from users’ accounts without warning as part of an infrastructure upgrade. Many Redditors were upset to discover that their chat histories from before January 2023 were no longer accessible. Reddit claims they only migrated data from 2023 forward during the transition to the new chat infrastructure. Some users were able to retrieve some of their old messages by requesting their Reddit data, though others reported that not all messages were recovered. Along with this change, Reddit has recently made other unpopular decisions like ending Reddit Gold, showing a lack of communication and consideration for users’ sentimental attachment to their online data.
What is much more likely is that you didn’t delete all your comments and posts. Reddit “listings” only go back 1000 items and if you delete an item from there older items don’t pop into view. So if you deleted all comments visible from your profile and you had posted more than 1000 comments you effectively never deleted all your comments.