Gmail can read your emails and attachments to train its AI, unless you opt out
(www.malwarebytes.com)
that's true, but I think it's in the phrasing, they describe it as a shortage of human made content. the bigger issue to note is the lack of ability to identify human made content. IE you give it reddit and our e-mails, there's plenty of human made content on there... but nobody knows what percentage of it is actually bots or AIs.