Usernames on our site get reverted to DEL names with a string of numbers after long periods of inactivity on the account.
It does not mean your account was hacked, and it does not have any worrisome implications. Sometimes DEL usernames do create login issues and password issues. Changing your username will fix those problems.
We can simply change that username for you, if you write into firstname.lastname@example.org with the email associated with your account. Please have 3-5 username options ready for us to change it to!