You could also downvote on the desktop site by using the RES keyboard shortcut

Older OSes did that, but modern ones usually just do the equivalent of format /q in DOS (write new filesystem metadata only, don’t check for bad sectors)

It should be possible to detect non-ads by downloading different versions of the audio file and checking which sections are identical, but you’d need some way of detecting transitions between sections.

If the ads use a voice actor who doesn’t talk on the podcast, maybe you could try to detect that.