автор The server creates a 'root'@'localhost' superuser account. The server's action with respect to a password for this account depends on how you invoke it:

With --initialize but not --initialize-insecure, the server generates a random password, marks it as expired, and writes a message displaying the password:

[Warning] A temporary password is generated for root@localhost:
iTag*AfrH5ej

With --initialize-insecure, (either with or without --initialize because --initialize-insecure implies --initialize), the server does not generate a password or mark it expired, and writes a warning message:

Warning] root@localhost is created with an empty password ! Please
consider switching off the --initialize-insecure option.