Time zone, after reboot comes back to SYSTEM (Debian Bookworm)

Hi guys,

I login to MariaDB and I do:

MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE 'time_zone';
+---------------+--------+
| Variable_name | Value  |
+---------------+--------+
| time_zone     | SYSTEM |
+---------------+--------+
1 row in set (0,001 sec)

After it I do:

MariaDB [(none)]> SET GLOBAL time_zone = 'Europe/Rome';
Query OK, 0 rows affected (0,004 sec)

And I have:

MariaDB [(none)]> SHOW GLOBAL VARIABLES LIKE 'time_zone';
+---------------+-------------+
| Variable_name | Value       |
+---------------+-------------+
| time_zone     | Europe/Rome |
+---------------+-------------+
1 row in set (0,001 sec)

After a reboot, like what I wrote in the subject, the time zone value 
comes back to system.

I did from command line:
# timedatectl set-timezone Europe/Rome

I have:

# timedatectl
                Local time: lun 2023-11-06 09:31:30 CET
            Universal time: lun 2023-11-06 08:31:30 UTC
                  RTC time: lun 2023-11-06 08:31:30
                 Time zone: Europe/Rome (CET, +0100)
System clock synchronized: yes
               NTP service: active
           RTC in local TZ: no

I inserted the timezone in 50-mysqld_safe.cnf

But after a reboot I have always the value sets on System.

I'll check asap from Knime if the timezone issue is fixed but I think I 
did everything to fix it or I should do other things?

Regards.
^Bart