It's meant to blend and rotate the current state and the rotated image. The capture of the current state is wrong, it's just giving a blue square filling quarter of the screen.
I think it's because it doesn't have a layer; we need to copy/paste something like ScreenshotLayer
Fixed in work/d_ed/screentransform, just needs a cleanup
A possibly relevant merge request was started @ https://invent.kde.org/plasma/kwin/-/merge_requests/8216
Git commit 348b35e092a2bbd99c4a7f17a7daf78961a52264 by Vlad Zahorodnii, on behalf of David Edmundson. Committed on 13/10/2025 at 11:38. Pushed by vladz into branch 'master'. plugins/screentransform: Fix pre-rotation grab Without a viewport explicitly set nothing seems to be captured. M +2 -0 src/plugins/screentransform/screentransform.cpp https://invent.kde.org/plasma/kwin/-/commit/348b35e092a2bbd99c4a7f17a7daf78961a52264
Git commit 59b7a5fcd17401c89be2d2a377a0c54a2e4a763c by Vlad Zahorodnii, on behalf of David Edmundson. Committed on 13/10/2025 at 18:45. Pushed by vladz into branch 'Plasma/6.5'. plugins/screentransform: Fix pre-rotation grab Without a viewport explicitly set nothing seems to be captured. (cherry picked from commit 348b35e092a2bbd99c4a7f17a7daf78961a52264) M +2 -0 src/plugins/screentransform/screentransform.cpp https://invent.kde.org/plasma/kwin/-/commit/59b7a5fcd17401c89be2d2a377a0c54a2e4a763c