This is version 1.8.3 of PHPExcel, which is based on version 1.8.2 and has been modified to work with PHP 8.3. There are no additional enhancements nor bugfixes in this version.
Tests work in general, but reveal lots of problems due to changes in PHP and PHPUnit over the past decade. Just enough to see that every test produces a result without raising general problems.
PHPExcel last version, 1.8.1, was released in 2015. The project was officially deprecated in 2017 and permanently archived in 2019.
The project has not be maintained for years and must not be used anymore. All users must migrate to its direct successor PhpSpreadsheet, or another alternative.
PHPExcel is licensed under LGPL (GNU LESSER GENERAL PUBLIC LICENSE)