Prefer non-var properties
This warning category is spelled [prefer-non-var-properties] by qmllint.
Prefer more specific type over var
What happened?
You defined a property in QML with type var instead of a more specific one, like int or string for example.
Why is that bad?
This affects the readability of the code and the QML tooling can't apply specific type optimizations.
You should avoid using var as property type for properties that always holds the same type. To avoid false positives, qmllint only warns about readonly properties with simple bindings. In other cases, it may not be able to distinguish properties that have to be var, because they need to hold multiple types, from properties that always hold the same type.
Example
import QtQuick Item { readonly property var myP: 42 }
To fix this warning, replace var with the specific type.
import QtQuick Item { readonly property int myP: 42 }