How to remove header banner image?

Nextcloud version (eg, 12.0.2): 13.0.2
Operating system and version (eg, Ubuntu 17.04): Linux 4.9.0-6-amd64 #1 SMP Debian 4.9.88-1+deb9u1 (2018-05-07) x86_64 GNU/Linux
Apache or nginx version (eg, Apache 2.4.25): unknown
PHP version (eg, 7.1): 7.0.30

The issue you are facing:

Since last update to 13.0.2, there is an image in the Web UI frontend header. The image changes each time the page is reloaded, resulting in the header with its icons not to be well visible often. The banner images are obviously only stripes of much larger images, resulting in strange-looking headers with parts of animals or landscapes, which doesn’t make sense. I’d like to get back a one-color banner. How to do that? In the theming settings I haven’t found corrseponding settings.

EDIT: Found out that that image disappears, if I disable the “Unsplash” app. However, for the login screen I’d like to keep the “Unsplash” images, but not for the header banner.

Steps to replicate it:

  1. Just update to 13.0.2, no settings changed.

Thank you!

then report it to the developers: https://github.com/jancborchardt/unsplash/