Could you share a screenshot with us which shows what the notifications look like? In addition to disabling them in the app, you could try disabling the notifications on your account page as well to see if that does the trick.
In case the app lets you know that a new episode is out, you can simply ignore it and focus on listening to other stuff you enjoy - the app would eventually stop recommending you that podcast and would instead replace it with something more relevant to your listening habits.
I will try to get a screenshot! Happily it has not happened since I complained.
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