I'm not sure it actually is. Free Gmail is limited to 500 emails a day, but Workspace accounts are allowed up to 2000, so this this spammer has to be using a Workspace account.

I've worked at a start up where the marketing team just had a `marketing@startup.com` email that was just like any other email in Google Workspace and used that for all marketing communications. Eventually they bumped up against that limit and a couple of engineers had to help them troubleshoot and there were enough blog and stack overflow posts at the time about hitting the limit to make make me think what they were doing wasn't uncommon.

When you consider the scale of Gmail and that this is almost certainly a Workspace account so they're mixed in with business customers, I'm not sure how much of an anomaly 10k emails a week actually is.