Yes, SafeSearch is enforced in incognito mode for Google, Bing, and DuckDuckGo on every browser, every device:

If you are seeing restricted content then you need to find the reason. Check your installed apps looking for a security type app with a web filter feature enabled as this will tunnel your browsing through their proxy servers (where they can inspect all your internet traffic).

Contact Kibosh Support for assistance.

SafeSearch Lock-In prevents the use of non-SafeSearch enforced browsers / search engines.