A few months ago podcast tracking service Chartable announced they were shutting down:

https://chartable.com/

and in the last few days they have turned off their domain chrt.fm . Unfortunately it looks like lots of podcasts didn't get the memo and they are still trying to use them and thus the podcasts downloads are broken.

You might want to contact podcasters you know to let them know.

Note they way things seem to work with podcasts is the download URL contains a series of other tracking URLS (often at different companies) that are redirected to one by one.

So the URL:

https://chrt.fm/track/4EB79A/tracking.swap.fm/track/6bpBPtHL977KJxLX2zPs/traffic.megaphone.fm/GLSS6742777722.mp3

redirects to:

https://tracking.swap.fm/track/6bpBPtHL977KJxLX2zPs/traffic.megaphone.fm/GLSS6742777722.mp3

which redirects to:

https://traffic.megaphone.fm/GLSS6742777722.mp3

which then does a 302 to somewhere else (but using a DB lookup rather than just stripping the URL)