An error occurred while installing the database: │ │ mysql said: ERROR 1819 (HY000) at line 1:

 Fixed this by creating the phpmyadmin user before installing phpmyadmin:

CREATE USER 'phpmyadmin'@'localhost' IDENTIFIED WITH 'caching_sha2_password' BY 'Phpmy@dm1n';
GRANT ALL PRIVILEGES ON phpmyadmin.* TO 'phpmyadmin'@'localhost' WITH GRANT OPTION;

Then:

sudo apt install phpmyadmin

When prompted for the password, enter the password provided when creating the user.

Hope it solve the phpmyadmin installation process.