The plugin is GDPR compliant. You can read about which options have been added to make it compliant.
Among the plugin options in YITH > Abandoned Cart > Settings, you can choose whether saving the abandoned carts of guest users. Specifically, you can add a checkbox for guests so they can agree with the use of their email by the plugin.
The checkbox text can be customized, as well as the time it takes to identify a cart as ‘abandoned‘. If you decide that the cart has to be left for 24 hours before it’s marked as abandoned, you’ll have to update your policies and include this time there.
If a user wants to get their data deleted from your store, the plugin uses the WordPress built-in feature which you can use and also the user data related to their abandoned carts will be removed.