Created attachment 141052 [details] comes from https://download.osgeo.org/libtiff/pics-3.8.0.tar.gz kolourpaint fails to open this tif file. gwenview can open it.
A possibly relevant merge request was started @ https://invent.kde.org/graphics/kolourpaint/-/merge_requests/9
Git commit 7466945e821419140f3cd02be7e90946ad61c4ee by Albert Astals Cid. Committed on 29/08/2021 at 20:09. Pushed by aacid into branch 'release/21.08'. Use the QImageReader::read variant that gives you an image even if it thinks it failed M +6 -1 document/kpDocument_Open.cpp https://invent.kde.org/graphics/kolourpaint/commit/7466945e821419140f3cd02be7e90946ad61c4ee