This bug started happening yesterday (July 16th) for me.
Another important factor is that every browser on iOS and iPadOS are affected due to them being reskins of Safari.
How to reproduce:
On any Apple device, open the DevForum (If you are on macOS, you have to use Safari)
This is additionally happening for videos that I believe are from other regions, I cannot play them. Some images from other regions, I cannot see them.
I think some regional blocking is happening on the forum, but when using any browser, I cannot see certain videos (but I can somehow see the thumbnail) and I cannot see some uploaded images.
I think this is a regional issue, but in your case, I think it’s just an issue with safari. I’m not an expert and don’t know if it’s possible but what happens when you downgrade safari?