No, this is not a new event, but the notices from third party watchdog/monitoring services are creating some confusion about that.
In 2018, MyFitnessPal user emails, usernames, and hashed passwords were compromised: https://content.myfitnesspal.com/security-information/FAQ.html
We alerted users at that time and have also required all MFP users to reset their passwords. The list compromised in 2018 is the subject of the current reports from these third party watchdog services because the list was only just now released. But as a result of the required reset, this list of passwords released from the 2018 breach is no longer valid on MyFitnessPal because the passwords used before then were disabled and had to be reset by users.
We continue to encourage people to use unique, complex, and strong passwords for all their accounts and to remain aware of scammers to further protect themselves.