Podcast Art Not Updating from Soundcloud

Well, looking at the actual file shows the size to be as you stated and thus within parameters: evidently the forum software had increased the size in reformatting it.

Looking at your podcast in the Podcast app (on Catalina) showes the old image, but subscribing (where the feed is read directly) shows the new one: it can take several days for the online podcast to catch up so that is probably the explanation, and it's just a question of waiting provided you changed the name of the image. Obviously I can't check that. If you didn't it, won't update because Podcasts caches the image and so it would have no way of knowing the image had changed.

Yes, I would have expected it to have appeared by now. However I see you haven't added an episode since May: are you planning to add an episode in the near future? That might kick Apple Podcasts into replacing the picture. Failing that, or if you aren't able to add an episode soon, you could try contacing Podcasts Support - they may be able to refresh the feed. https://podcastsconnect.apple.com/contact-us . Give them the podcast's ID as well as the title: id1104728957

Posting the image here tells us nothing reliable since the forum software may tamper with it - however, that said, the dimensions are as described but the file size (as posted here) is 512 kB which is over size. If you post the URL of your feed I can check the actual file to be sure.