Due to the Firefox recent update which is Version 72, the Native browser opt-in prompt will no longer display automatically.

So Firefox users now will only see the Custom prompt (with the chicklet) by default even if the prompt is set to the native browser in your dashboard.

Once they click on the "Subscribe" button on the custom popup that's the only time the native browser prompt will appear.As much as we wanted to keep the automatic native browser prompt on Firefox, unfortunately, this is a setting implemented by Firefox which we cannot do much about other than the workaround that we came up with as mentioned above.