I personally (re)listen to three dead podcasts that I love to death:
The Onion's podcast The Topical, which is classic onion stuff. I actually started listening to it from the very beginning when it started in 2020, and I'm still sad it's dead, but at least the last episode really knocked it out of the park!
The Hard Drive's podcast The Super Mario Bros Super Show Show, which I'm sure you can't guess what they talk about (it's the DIC Entertainment Super Mario Bros Super Show). It at least makes more sense why they shut down, since they watched all the episodes, but it still sucks. Their other podcast also appears to have shut down in 2023, too.
Markiplier's podcast The Distractibles, which I'm not sure if they have actually shut down, but I haven't checked them in a while. They're mostly a backup if I get bored of listening to the other two again.