AntennaPod is great but most ads are directly injected into the files these days. The best you can do is skip them when they come up. AntennaPod allows you to set custom skips for the start and end of individual podcasts though which is useful.
I read that its a good idea to use a vpn to a very small, rather poor country. When the podcast has dynamic ads, it may not have one for your country and you can get it ad free. Havent tested it though.