Yes, Podcasts in iOS11 is a complete mess.
I kept randomly getting old episodes show up in my subscribed feeds. So I would go into the app and press the ellipses next to the episode and "Delete from Library". Ok great, offending episode is gone.
Later, I find out the entire podcast show is unsubscribed. I wonder what's going on so I resubscribe.
Old (different) episodes keep showing up in my feed. Yet again, delete from library and later see that show is unsubscribed.
Come to find out "Delete from Library" unsubscribes from podcasts, when there's a "Unsubscribe" option right above this!!!
And what happens if I press "Unsubscribe"? It unsubscribes but KEEPS the offending episode in my feed! WTF!!