New Tab Page
Supported on: Firefox 68 or later, Firefox 68 ESR or later
Registry
HKLM
Software\Policies\Mozilla\Firefox HKCU
Software\Policies\Mozilla\Firefox Value name: NewTabPage
Enabled: NewTabPage = 1
Disabled: NewTabPage = 0
Description
If this policy is disabled, the new tab page will be blank. If this policy is enabled or not configured, the new tab page will be the default.