No new-feed-url tag in feed after redirect?

In the Redirect this feed to new URL field, a client has entered the new feed address: https://servingworlds.com/feed/podcast/john-mierau-serving-worlds/. The prior feed URL was https://servingworlds.com/feed/podcast/serving-worlds

The 301 redirect is working fine (though I’m confident it was 302 an hour ago, which maybe was actually temporary temporarily. ?) But I do not see the new-feed-URL tag in the current feed. My experience with moving long-running shows provides plenty of evidence that there are some older legacy apps that will only update their direct links when they encounter both the 301 redirect AND confirm the new feed has the new-feed-url tag in place.

What do we need to do to make that tag appear in the redirected feed? And, if it’s a behind-the-scenes thing, consider this a formal request to add the following:

https://servingworlds.com/feed/podcast/john-mierau-serving-worlds to the new feed at https://servingworlds.com/feed/podcast/john-mierau-serving-worlds/

Cheers!