Firefox monitor keeps finding old, long-closed accounts where the service was breached So far, I think every breach was post-account-closure. Though it is obvious that "close my account" does not equal "delete my information" at any time.
Reminds me of one account where there was no "close account" button, so I contacted support to request account closure. To my surprise, they said they do not delete accounts or account information ever, and my best option was to fill the account information with gibberish