New users now have to opt-out of training on their data - it is enabled by default. For existing users, during the transition they updated their terms and let you know about the change in policy, giving you an option to opt-in or opt-out. Opt-in was the default selection. Just today they AGAIN updated terms, presenting a click-through form on first load that looks like a permissions check (e.g. the standard dialog to enable access to the file system that we're conditioned to click-through). It was actually a terms-of-service update with opt-in selected by default, even if you already explicitly opted out. So if you hit enter to dismiss as you're used to doing, you just switched your account over to opt-in.