Hello iPregunta,
Thanks for the post! Being able to use the Podcasts app is always important, and we're happy to help out.
Knowing that the issue only occurs when your Mac is connected to the internet is helpful information. Try booting your Mac into safe mode next, and test to see if the issue happens then. This helps to rule out a few software causes: How to use safe mode on your Mac. Once you boot up in safe mode, test and click Apple menu () > Restart, and then test again.
You can also test this issue in a newly-created administrator account, which will tell you if the issue is system-wide or specific to the user account. Here's How to test an issue in another user account on your Mac.
Let us know how the tests go, and be sure to include your exact current macOS version as well, found under Apple menu () > About This Mac.
Best wishes.