After updating the newsletter plugin to V 8.1.0, I received the error below after editing a newsletter user. I just wanted to assign the user to a second list. After a rollback, editing the user was possible without any problems. I use newsletter version 8.0.9 with WordPress 6.4.3. I use MariaDB 10.6.16 as the database.
Database error. If you were saving a newsletter try a table upgrade from the status panel.