Hi Chris, hope you don't mind me contacting you about your post regarding V2H with your Enyaq and Sigenergy DC charger.
I've got a MY27 Enyaq Coupé vRS with a Sigenergy DC bidirectional charger and I'm seeing remarkably similar behavior to what you described.
V2H establishes successfully and the car starts discharging, reaching around 4.5...