Okay, it keeps getting weirder. I thought it might have been an issue with WepP support, but now I'm not sure anymore.
Can you open this page, and tell me what it says?
Does my browser support WebP?
Quick way to check WebP support in your browserihordiachenko.github.io
It's a test to see if your browser and configuration support WebP properly.
View attachment 18535
It may have to do with your browser's cache, following the forum software update. Have you tried deleting your browser cache / temporary data? It's worth a try.