EU data residency
Mixpanel offers an EU residency option that keeps data in Frankfurt. If you enable it (recommended for any EU traffic), your privacy policy should say so — "Mixpanel processes EU user data exclusively in the European Union under our EU residency configuration." Without that flag, data flows to US data centres and triggers the SCC chain.
What gets sent
Mixpanel's default SDKs collect IP, device, browser, OS, and any custom event properties you send. If you call identify() with an email or user ID, that ties events to a person — which must be disclosed.