Q: How to force new Podcast subscription icon?

At some time in the past, one of my favorite podcasts (KCRW's Today's Top Tune) changed its icon. Now, the podcast has a different icon on my Mac than on my iPhone. I know this doesn't qualify as a major issue, but for someone who is very visually oriented, it's unsettling and confusing.

How can I force Podcasts to use the current icon? I already tried stopping subscription and deleting all episodes. Where is the old icon "stored"?