September update on my Nokia 6.1 Plus hasn't brought back the option to hide the notch. It's disappointing.
Personally, I think that they are waiting for Android 9 Pie as that will have native support for Notch, including hiding.
i.e our best bet is to hope that Android 9 is shipped ASAP to Nokia 6.1 Plus, so that we can hide the notch using Google Intended mechanism.
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