Johan van der Wijk

This plugin disables all WordPress updates (core, plugins and themes). This can be useful if you have multiple environments such as a live and staging server and you don’t want your users to use the update functionality.
This plugin not only disables the update mechanism for the core, plugins and themes, but it also removes the update menu item from the left navigation menu in the admin dashboard.

Disable Updates for WordPress Core, Plugins and Themes

Disables the WordPress update checking and notification system for all core, plugin and theme updates.

KZeni

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 <a href="https://github.com/KZeni/Disable-WordPress-Theme-and-Plugin-Auto-Update-Emails" rel="nofollow ugc">https://github.com/KZeni/Disable-WordPress-Theme-and-Plugin-Auto-Update-Emails</a>

Disable Theme and Plugin Auto-Update Emails

Disables the default notification emails sent by a site after an automatic theme and/or plugin update. Simply activate the plugin to disable these ema …

Disable Updates for WordPress Core, Plugins and Themes vs Disable Theme and Plugin Auto-Update Emails