This warning category is spelled [top-level-component] by qmllint.

QML top level type can't be Component

What happened?

You used the Component type as top level type for your QML file.

Why is this bad?

Your QML file already defines a component by itself. Using a Component type as a top level type will wrap your component into another unnecessary component.

Example

import QtQuick

Component {
    Item { ... }
}

To fix this warning, remove the extra Component wrapping:

import QtQuick

Item { ... }