WordPress introduced a powerful feature, the plugin auto-update. Similar to the “core” auto-update, where WordPress updates itself on minor version changes (for example from WP 5.8 to WP 5.8.1 but not from WP 5.8 to WP 5.9), now plugins can be auto-updated.
The feature is active only for new plugins installation and can be enabled/disabled for each plugin.
Now the question is: should this feature be enabled for Newsletter?
We have no evidence the auto-update could create problems even if there are core tasks, like the newsletter autogeneration, the background delivery, and few others that could be interrupted and restarted with a new plugin version.
Usually, that should not be a problem, but if we need to release an update with a breaking change, of course, we cannot grant everything will work smoothly under every circumstance.
So, if you make intensive use of Newsletter, with our Automated and/or Autoresponder addon, probably you should disable the auto-update feature for Newsletter and update it manually under your control.
Addons, vice versa, like Automated and Autoresponder, are not auto-updated by WordPress being stored in our repository and not the WP repo (you should not even see the auto-update on/off option).