Good plugin as far as functionality.

The reason for the 1 star is the plugin author deploys virus/malware like behavior.
The plugin will create a newsletter popup multiple times daily AND have the audacity to pin this popup within the firefox toolbar.
The author has been warned of this behavior several time on his discord AND within the reviews here but only looks to implement more atrocious behavior.
If he's willing to do this, what else is he doing?