Class "PhpOffice\PhpSpreadsheet\IOFactory" not found

@ty10086,
I ran the composer require phpoffice/phpspreadsheet in my project root and it started working.
For now you can run this command to make it work.

It should be in modules composer file. I am adding patch to modules composer file. Once it will be in new release, it will work on module download with composer.

@shailja179 Thanks Bro.
I tried
composer require phpoffice/phpspreadsheet in Drupal root file;
composer require phpoffice/phpspreadsheet -W;
composer require phpoffice/phpspreadsheet:^1.28 -W (in composer.json is 1.29)
some errors as attchaments show,with new problem.
problem 2/3/4:Drupal needs running php 8.1.7(8.x)
prolem 1?
problem 5?
I checked mysites/admin/reports/status is ok.

@shailja179
I try to downgrade to version 10.1.12---->10.1.0-alpha1 by composer composer update "drupal/core-*" --with-all-dependencies,and root composer.json "minimum-stability": "stable",----->"minimum-stability": "dev"----> composer require phpoffice/phpspreadsheet ----->Using version ^1.28 for phpoffice/phpspreadsheet
in feeds_xslx/composer.json keeping :"phpoffice/phpspreadsheet": "^1.29",

It is worked for me.

10.1.12 not worked well.

I am using Drupal 10.1.x and Php 8.1. Its working for me.
See the screenshots.

@shailja179
Finally, I root+composer config -g --unset repos.packagist --->composer require phpoffice/phpspreadsheet:1.29.0 -W

This is work for me on Drupal 10.1.2+php 8.1.7.