There was nothing wrong. It's just the image hosting site did not accept this format. I tried to upload a .webp image on imgur and it doesn't work. This is what it shows:
It also happened to me, but I wasn't using imgur as my image hosting site I used
imgbb.com. Although, it didn't display any error like that of imgur but still yet the forum could render the image, so I had to delete the whole post because I was quoting an Op for visibility.