I noticed that the database "Root password" change fuctionality does not actually change the password.

Although it seems that the new password is changed, actually it is not saved. The proof is that the old password has to be used to access (PhpMyAdmin) the databases (mySql, MariadB).
The only way to change the password is via SSH:
mysql -u root -p
ALTER USER 'root'@'localhost' IDENTIFIED BY 'NewPassword';
The issue has already been reported.
I'm using Debian 11, aapanel ver. 6.8.33