Cluster of red 'dead looking' pixels appear randomly

Help
,
1

While using the PC I noticed that a small cluster of red pixels can appear seemingly randomly. So far has happened about 3-4 times within the last month.

My first thought was of course that my display is giving out, except that the cursor can go over them and they appear in screenshots.

I assume it’s not a bug. How would I go about finding what (broken window/app) might be causing it?

A screenshot of the ‘dead’ pixels:

so_called_dead_pixels
so_called_dead_pixels244×167 1.21 KB

Also a screen-recording of them moving (relative to display) when switching to different display scaling-s: https://files.catbox.moe/qlwrhw.mp4 (Compression makes it a bit hard to see)

System Info (what else?):

NixOS “Warbler”
KDE Plasma Version: 6.3.6
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.2
Kernel Version: 6.12.48
Wayland
Nvidia Driver Version: 575.51.02
2

Turns out it is just KDE Mouse Mark utility. Learned something new about the Plasma Desktop.

Holding Shift + Meta draws with your cursor and Shift + Meta + F11 to clear all annotations on screen. Will definitively make use of the arrow annotation with Ctrl + Meta + Shift.

Settings for it are in Window management > Desktop Effects > Appearance > Mouse Mark.

Screenshot_20251119_225804
Screenshot_20251119_2258041918×1033 174 KB

Hope it helps someone, should they have found out about this feature in the same unfortunate way.