Code
Based on QTBUG-11030:

import QtQuick
import QtQml

Window {
    height: 400
    width: 600
    visible: true
    Component.onCompleted: {
        console.log("Assigning constants...")
        let [a, b] = [1, 2]
        console.log(a, b)

        console.log("Swapping variables...");;;
        [a, b] = [b, a]
        console.log(a, b)
    }
}

 
Steps to reproduce

1. Save the code above into Main.qml
2. In that folder, run qmlformat --write-defaults
3. Run qmlformat Main.qml
4. Edit .qmlformat.ini to change SortImports from "false" to "true" and repeat #3
5. Edit .qmlformat.ini to change SemicolonRule from "always" to "essential" and repeat #3
6. Run qmlformat --semicolon-rule=essential Main.qml

Outcomes

• (Step #3) The import order is not sorted, every line in Console.onCompleted has a single semicolon (Expected)
• (Step #4) The import order is now sorted (Expected)
• (Step #5) Same as Step #4 (Not Expected)
• (Step #6) Only the "Swapping variables..." line has a semicolon (Expected)