This change moves the old app/plugin_installer/checkOnStart setting key to a new plugins/automatically-check-for-updates key, and switches the default value to enable automatic checks.
This is designed to switch all existing QGIS users to the new default behavior of checking for plugin updates at startup (at a maximum of once every 3 days).
It is intended to offer a better QGIS experience to our users, by proactively informing all users when plugins should be updated, ensuring that ALL users are more likely to upgrade plugins and get the bug fixes for plugins promptly.
Enterprise users who have customised this setting in their deployments will need to adapt their scripts for the new setting key.
Additionally, the option to control the number of days between plugin startup checks has been removed and is hardcoded at 3 days.
This feature was developed by Nyall Dawson