Sorting feed items

Hi Team,

First, we are trying to create the feed with “published date” by ascending order (like post).

As you wrote on this article below, I set this up the code on functions.php, but it seems some other issues raised up. (WP: 5.7.2 and TEC: 5.8.2)

https://theeventscalendar.com/knowledgebase/k/customizing-the-rss-feed/

Looking inside of the feed, <pubDate> shows the “event starting date” with GMT.

The feed is a normal WP feed (as /feed).

Q. How can I accomplish my goal? (Sorting feed items ascending)

Q. Or how can I change the <pubDate> from “event starting date” to “post published date”?

Please let me know what I can do.

Thank you so much for your support in advance.