Hi,
Regarding the deletion of subscribers in Acymailing, please be advised that once deleted, they cannot be recovered. In this case, I would suggest restoring a recent backup of your website to retrieve the lost subscribers.
Additionally, I noticed that you are currently using an outdated version (February 2022) of Acymailing. It is highly recommended that you regularly update your Acymailing to ensure optimal performance and security. The current version available is 8.6.1.