Clear SXG Cache after changing primary domain

Hello -
Recently changed a sites primary domain and set a 301 to the new one.
The original domain had Signed Exchanges turned on within CF.
Google is detecting the 301’s and updating their index however we are still seeing listings for the old domain and when you click on those links you see a brief webpkgcache URL before the redirect hits.

I have tried this procedure (Google: Signed Exchange Update Cache API Reference) and get a response of OK however it doesn’t appear to affect Google removing the webpkgcache interstitial URL.

I’ve reached out to CF support but they haven’t provided anything of use yet. Anyone else dealt with this issue? How were you able to force Google to flush their SXG cache for an entire domain?