Having a ticket contain a blacklisted tag will prevent Unbabel from initializing, effectively disabling translations and blocking any data from reaching Unbabel. In order to activate the feature, you need to add the tags you wish to have such effect to the Blacklisted tags field under General Settings, on the Settings page.
Once defined here, you need to add the tags to the Zendesk tickets that you don't want to have translated. There are several ways to do this, from using trigger to simply adding them manually. Just be careful not to have an agent that will fire the translation attempting it, as the ticket will initialize before you have the chance to add the tag!
Once the Blacklisted Tags are saved and enabled, a message will be displayed within the Unbabel widget informing the agent the ticket contains a blacklisted tag. The same tags can be removed by the agent if necessary.