Cover art is not displaying on my desktop

I downloaded a podcast episode and the download in addition to the audio file also provided the podcasts cover art. A 3000x3000, 284kb, PNG file. I embedded the cover art using Mp3Tag but its not displaying on my desktop. The audio file type is a MP3.

I tried using different cover art and the results were the same. I also installed a tool that removes any excess padding and that didn't fix the issue either.

I converted the MP3 file to FLAC to see if it would fix the issue and it did. But the obvious drawback is the larger file size. Whats causing this one specific MP3 to not display cover art?

From the distance this is more or less impossible to say - as you do not supply that file for others to investigate.

But what you could do straightaway: check the file for problems.
See this thread for links to checking tools:

Here's a link to the episode. There's a download option.

https://www.podchaser.com/podcasts/japan-station-a-podcast-about-747859/episodes/understanding-otaku-and-akihab-51454700

MP3val and MP3 Diags did not find errors. The Foobar2000 utility did not work.
Bitrate and Length are visible. No audio blips and the tags can be easily changed

I do not find a link to download - and even if I downloaded the file it would only show that either my file is OK or might have a completely different problem.

I would use a copy of the file and reduce the cover size to something like 1000x1000 and see whether it works.

What do you mean by this? Where do you want to see the cover art?
Your screenshot of Mp3Tag shows the cover art for the mp3-file.

I embedded the cover art but the file icon itself has not changed. The top image shows this.

Where exactly did you get this 3000x Pixel cover?

You have associated .mp3 with a software that uses that icon:

The image was provided with the audio file when I downloaded it using the RSS feed link. Like I said in the description, I tried other images which were also at smaller dimensions. Like 1000x1000

I have file extensions enabled. It shows .mp3 in the name which is shown in the screenshot. Regardless, when I successfully embed cover art, the foobar icon is usually replaced with the cover art.

Where exactly "on your desktop" you expect to see the cover art?
In your Windows File Explorer?
In a player software? If yes: Which player?

I just added a different picture to the file

And it shows up like that in the explorer

I added a picture with 4000x3000 pixel

and that looks like this:

By desktop I mean file explorer. Their inextricably linked, try turning off the file explorer exe in the file manager and your desktop vanishes. But I guess I need to be more specific since you might think I am referring to an audio player.

Huh, weird. I tried a 500x500 image and it still doesn't work. The file size is also not over 3MB because windows cannot handle cover art over that file size.

The same here:

On the left side you see the downloaded cover picture as 512x512 JPG.
On the right side you see the same picture embedded in the mp3 in the Windows File Explorer.
(My mp3 are associated with VLC).

That is why I suspected something is wrong with your file locally - could you download it again and see whether that helps

In list view (and also in detail view), Windows Explorer by default only shows the icon of the linked default app for MP3 files (e.g. VLC, Windows Media Player).

Displaying embedded cover images as file icons only works in the "Large icons", "Extra large icons" and sometimes in the "Tiles" view modes - but not in the list or detail view.

Nope, still not working. I downloaded a new file and embedded several different images. The issue seems localized to me for some reason. I also downloaded the file using three different software's. gPodder, Extreme Download Manager and GoSpeed. What could possibly be the issue?