Several weeks ago a new and very annoing bug appeared on my laptop using KDE Plasma 5. After logging in the I could see this for around 20 to 30 seconds:
Today I started my KDE Plasma 5 from the console, then logged out and saw this error message:
file:///usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/splash/Splash.qml: 50:13: QML Image: Binding loop detected for property "sourceSize.width"
Then I disabled the default splash screen named „Breeze“ in systemsettings5 -> „Workspace Theme“ -> „Splash Screen“ and set it to „None“.
Before I saw this message I didn’t realize that this was the splash screen :P
Solved, perfect :)
I submitted a bug report, see here.