SOLVED!
When I read the Apache's logs, identified the different module between PHP 7.4 and downloaded timezone database (DLL).
PHP Warning: PHP Startup: timezonedb: Unable to initialize module\nModule compiled with module API=20190902\nPHP compiled with module API=20190529\nThese options need to match\n in Unknown on line 0
The PHP 7.4 used in this version of UniServer (XIII) is development version (alpha or beta [-dev suffix]) released 6 months ago. When the official PHP 7.4 was released in November 28th, 19.
Solution:
Now, I'm using the UniServer Zero XIV with PHP 7.4 as default version. It uses 2019.3 timezone database' version and datetime is now correct.