Seeking Insights on Segment and Mixpanel Integration Best Practices

Hey, anyone experienced with the Segment > Mixpanel integration? We have deployed the Segment tracking on our website + Mixpanel Destination and event's mapping. However in our testing Mixpanel property it seems like it is not processing UTMs and Referrer data correctly. https://docs.mixpanel.com/docs/tracking-best-practices/traffic-attribution

Mixpanel’s Javascript library tracks all UTM tags by default. Mixpanel’s Javascript library will track Initial Referrer and Initial Referring Domain and append them as a property to any event that a user completes