Why is MySQL allowed as root with any password?

Question

MySQL

The problem is this:
There is Debian

Debian GNU/Linux 10 (buster)

and mysql

mariadb Ver 15.1 Distrib 10.4.12-MariaDB, for debian-linux-gnu (x86_64) using readline 5.2

after installing mariadb ran

mysql_secure_installation

Set a password, and reload privileges. Under root user:

mysql -uroot -p

lets with a password, without a password and with the wrong password. There are no errors in the logs