Screen Mirroring

From what app are you streaming when this happens?

I can’t replicate the behavior from the Apple TV app. It seems to stream fine from a midpoint, for Apple TV+ sources, iTunes Store movies, and local library (downloaded/synced) videos. And I can scrub the timeline to go to a different continue point.

If screen mirroring or streaming isn't working on your AirPlay-compatible device - Apple Support

I tried various Safari web videos and YouTube with my setup, and it never restarted from the beginning. Not sure why your expense is different.

But as the support document advises: “If you still can’t use AirPlay after trying these steps, contact Apple Support.”