Steps to reproduce:

• open/create Qt Quick UI or Application
• switch to Designer
• select an Item where you can change the color
• click into the colorchooser (sometimes the cross marking the point of click wanders 2-8 times to the up-right and changes the value)
• same behavior can be seen if you enter a value directly into the line edit of the color ('af00fa', 'ca00ac', ...) - first entered value does change once, but if you now enter the same value again it is accepted

Might be some rounding issue?