QML TextField text erronously capitalized on devic

Question

I'm building a Qt application for Android, and I can't figure out the reason a textfield behaves the way it does.

This code:

    TextField {
        id: usrField
        Layout.fillWidth: true
    }

somehow capitalizes the text that is entered in the textfield, but only on the phone. If I build it as a desktop application, it works the way it ought. The password field:

    TextField {
        id: pwField
        echoMode: TextInput.Password
        Layout.fillWidth: true
        Keys.onReturnPressed: {
            loginButton.accessiblePressAction()
        }
    }

works as intended, both on device and on desktop.

I've tried adding font.capitalization: Font.AllLowercase, but to no avail.

Any help is greatly appreciated. Any ideas?

Clarification: All letters are capitalized, not only the first. If I manually turn off caps lock and enter a letter, caps lock is automatically turned on again.