Interestingly it seems to still be a problem. I was a bit confused with this today - I had done a pull this morning and noticed I'm now unable to update cover images on the blog. The URL does not appear to be wrong or problematic, and I can access the webp directly in the browser - but it does not appear in the cover... Did a fix come out for this yet or not?

In addition to not displaying, it seems to also be duplicating the images in the media library per Github issue 173974.

I have the same issue my JPEG image is converted in webp format. And based on my reading, the %27 in the URL is not working too. I have the %27 in my image URL and can't remove it. So far nothing is working currently. 

Hello they already fix it at https://github.com/odoo/odoo/pull/170849 just be patient