I'm testing plasma-wayland-devedition-gitunstable-20170128-2117-amd64 and I noticed the bug described in the title. This does not happen when I scroll using the mouse wheel. It happens only under Wayland.
Likely fixed since the reporting of this bug; cannot confirm
Dr. Chapatin, can you still reproduce this?
cannot reproduce on Arch Linux (plasma 5.11.5) nor on neon dev unstable.
Great, let's call it fixed.