With the Google Sitekit plugin enabled, the warning:
Warning: Undefined property: stdClass::$slug in /wp-content/plugins/wp-fail2ban/lib/update.php on line 28
is visible at the top of wp-admin. The $item object passed in is missing the slug parameter, causing the error.
I’ve already raised a bug with google sitekit here: Missing slug parameter on auto_update_plugin filter · Issue #7086 · google/site-kit-wp (github.com) since this seems like an issue with them and not you, but, I am reporting it here anyway in case you want to add a check to avoid the warning occurring.
PHP is 8.1
Wordpress 6.2.2
fail2ban 5.0.1
Sitekit version 1.101.0