404 page in background

I read the note “The automatic screenshot is produced from a service on WordPress.com. There is no way to manually refresh the screenshot once taken. WordPress.com should refresh it within a few days.” but there is no image, just a 404 image.

Is something not working correctly?

Should I simply make my own workaround by inserting my own background image?

https://www.ads-software.com/plugins/ultimate-maintenance-mode/