No way to stop or suspend automatic podcast downloading.
I updated my podcast feeds and suddenly hundreds of old episodes started downloading or were in waiting state. (I only wanted the episode lists to update). After setting Check for new episodes = Manually, the podcasts continued to be downloaded. The only way I found to stop this was to delete the episodes or feeds.
There should be a distinction between automatic feed list update and automatic episode download.
Also a way to temporarily suspend automatic download e.g. when on a metered network.