In the GLPI reports plugin this shows up as
PHP Deprecated function (8192): Creation of dynamic property PluginReportsAutoReport::$plug is deprecated in /var/www/html/glpi/plugins/reports/inc/autoreport.class.php at line 57
See
https://stackoverflow.com/questions/74991682/php-8-2-dynamic-properties-deprecated-how-to-use-them-anyway-in-a-compatible-wa
for possible solutions. The options are to rework the class to not use dynamic properties, to extend stdClass, or to add an attribute.
Support will be dropped in PHP9, apparently, but that's not on the PHP version support grid yet https://www.php.net/supported-versions.php
I'd like to submit a PR, but I don't think I'm likely to do that any time soon, as I don't know the plugin code (or GLPI, for that matter) well enough.