Check out these:
Example of what it looks like:
It’s not all apps, and not even apps that were recently updated at the same time. Console shows 404 error, clearing cache doesn’t change it, and these same apps work fine on beta.flathub.org.
There may be more apps with this issue, I only checked a few
Edit: 2 more
Edit: I’ve confirmed the .appdata.xml of 2009scape is referencing non-404’d images, and I’ve created a PR to try to update it and see if that gets it unstuck
Edit: Still stuck. Rip