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All settings of the Plugin will be saved in the db.
Your Plugin can choose which table they wanted to store the setting into. Check the source code of your Plugin.
If your Plugins uses get_options(), then it will stored in the wp_options table
If your Plugins uses get_post_meta(), then it will be stored in the wp_postmeta table
If your Plugins uses get_comment_meta(), then it will be stored in the wp_commentmeta table
Your Plugin might also have created its own table to store the settings