If you have a Claude account, they're going to train on your data moving forward

Am I the only one that assumed everything was already being used for training?

This. It's the same innocence of people who believe when you delete a document on Google/META/Apple/Microsoft servers, it "really" gets deleted. Google most likely has a backup of every piece of information indexed by them in the last 20 years or so. It would cause envy to the Internet Archive.

With the privacy laws out there, I do genuinely think they eventually get purged even from backups. I remember there being a really cool YouTube video shared here on HN that google no longer has publicly, it was about the process of an email and all the behind the scenes things, like physical security into a data center, to their patented hard drive shredders they use once the hard drives are to be tossed. I wish Google had kept that video public and online, it was a great watch.

I know once you delete something on Discord its poof, and that's the end of that. I've reported things that if anyone at Discord could access a copy of they would have called police. There's a lot of awful trolls on chat platforms that post awful things.

My understanding is that for Gmail specifically, they keep a record of every email ever received regardless of deletion status, but I'm not able to find any good sources.