I've been using Podcast Addict, which had a one-time 3,50€ microtransaction to remove ads inside the app* but now also has a 10€ / year subscription to further support the dev and gain a few more features (which may have replaced the one time transaction? Hard to tell on my end)

*while the one-time purchase removed the ads from the app itself, it does not bypass ads being added into the feeds by the podcasts themselves (which are usually the ones that play "between" episodes)