Possible causes for files in the Files app/iCloud to suddenly stop displaying file previews?

Hello I hope this is the correct place to post this question though I actually may have a few questions in this post. I am not a developer by any means, I am a graphic designer and I am dealing with a peculiar problem on my iPad and I would like to know why it’s happening and what is causing it.

How does iPadOS/iCloud/Files app handle file thumbnail previews? Where are these images stored? What could suddenly cause an app on my iPad to stop showing the file preview thumbnail and instead display the generic app logo as the thumbnail preview for the files? This is the only file type to suddenly stop showing the actual file contents preview.

The file type I am referring to is a .afdesign file for the Affinity Designer app. I am sure there is not much I am able to do to revert the file preview back to the original contents but I am just curious what could cause the files to do that. I have already contacted Affinity support for help and they stated that this is an issue with iPadOS/iCloud not the Affinity app.

Though all of this started happening after I updated the Affinity Designer app. My project files before the update display the actual contents of the file in the preview thumbnail, after I updated in the beginning of February all my files started showing the generic Affinity logo as shown in the screenshot. People on forums said that this a “bug” and it happens randomly. But there has got to be a fix for this. Thanks for your help