Disables the default notification emails sent by a site after an automatic theme and/or plugin update. Simply activate the plugin to disable these email notifications (allows failure notices through unless setting is enabled to disable these as well).
This is a simple & lightweight plugin that simply uses the official filters made available as of WordPress 5.5 to disable these email notifications upon activation. It does let update failure notifications through by default, but the Settings => General page has a setting to disable these as well.
Check things out on GitHub at https://github.com/KZeni/Disable-WordPress-Theme-and-Plugin-Auto-Update-Emails
Screenshots
The Settings => General setting for also disabling failed update email notifications (successful updates are disabled simply by having the plugin active on the site.)