The reason for me updating PHPExcel to suport PHP 8.0 was becuase most of the time it was used as third party library and people don't want to make changes to thier existing codebase so this work like a drop-in solution if you just want to bump up your existing application PHP version without making too many changes.
If you are adding support to new project consider using its sucessor below.
PhpSpreadsheet, or another alternative.
PHPExcel is licensed under LGPL (GNU LESSER GENERAL PUBLIC LICENSE)