Blurrred posters if they are not scrapped posters

[ZombieHunter]

After you manually add or change images, you need to go to the movie, series, episode or library that you added the changes in and "Refresh Media" using "Scan for new and updated files," most likely. Images also need to follow the naming scheme.

How does this change the behavior?
I mean that's what I always do.

Again: If the movie/file server is down the images are blurred.

So Jellyfin (running on another computer and using "Upload Image") does not upload the images do its own directories?
But scrapping images from the web does?