The idea of a new Joomla! podcast was raised during Joomla! Day UK 2017 by an attendee who was keen to be its creator. I really would like to see this as there have been some great ones in the past. If you want to see this too, then feedback via Github so he is encouraged to make it happen. https://github.com/joomla/joomla-marketing/issues/109. Here's a link to some of the other podcasts that either still run or have run in the past.
I listened to this Podcast by Peter Bui a lot. http://joomlabe.at/ It's a really high quality production and a fantastic educational piece.
I only just found out about Joom Stew, and it's no longer being updated unfortunately, but there are still some episodes online. http://www.blogtalkradio.com/joomstew
How about a list of Google Hangouts that were attended by a few people and recorded? Pretty neat idea, let's hope they resurrect that again! https://www.youtube.com/channel/UCrY5f72iOIh7vzuc6OrekGQ
Another is the Tim Plumber Joomla! Show another one from Australia. https://itunes.apple.com/au/podcast/the-tim-plummer-joomla-show/id1142056156
In any case, if you want another podcast, either volunteer, or share your ideas here: https://github.com/joomla/joomla-marketing/issues/109 so others can run with them. And of course, we're always looking for new bloggers on Joomla! London