I suspect this service will be abused by all kind of people and will have to shut down.

It's been up for years

or quickly subsidized by three letter agencies

yeah that is what I was thinking "Ah how cute, it's the ops team from a state" lol but probably not - didn't look into / not interested but guessing it's an existing info sec consultancy behind it that do sometimes work those kinda places or banks etc.

Never heard of this before, and I think the mail Google sends you specifically says it is safe to ignore it if it didn't come from you.

Has this recently changed?

I did not know that. Could you elaborate?

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.

In one of the pictures the Claude Code author had 2.4m tokens on his last his prompt.

I don't understand how that would fit the context window. But with prompts like that your workday would be very boring if you had to run one single agent and wait for it to be done.