The link to SVGs files at https://www.digikam.org/contribute/splashscreens/ links to older versions in KDE repository which wouldn't open with up to date Inkscape. It should have been changed to link to Github versions. As a side not, I would like to suggest you to make use of images from Pixabay website for splash screens, which are all CC0.
No : https://invent.kde.org/websites/digikam-org/blob/master/content/contribute/splashscreens.md#L14 This is the source of splashcreens.md page which point to https://invent.kde.org/kde/digikam, which is in fact the gitlab repository. We don't use github and the migration from KDE git server to gitlab have been completed few days ago... Gilles Caulier PS : For the Pixabay idea, i would to suggest to create a new file in bugzilla with the idea to add to end user the choice to select the photo to this web site. We have already this file open : https://bugs.kde.org/show_bug.cgi?id=384689