I looked it up and am still a bit murky. Is this a way for them to compact their stored data about you? Seems kinda like that, assuming they're doing away with the stored conversations (deleting them?).

When you asked it to "Remember this", it stored it in a flat file, which was injected into each context window as a pre-prompt. So then in any new context window, if it became relevant, it would know that context. Now, the memory files are being preserved for paid subscribers, but they are being deprecated. So for now, it can still find that information, but only when asked to, like here: