How to avoid tethering?

Some manufacturers inexplicably don't let the user boot into Safe Mode, which I think is one of the most user-unfriendly moves ever.:-\

Try this -- the next time the QR code shows up, immediately swipe down the Quick Settings panel and see if the Hotspot/Tethering setting is toggled on. You might have to edit the Quick Settings panel right now to make sure the Hotspot toggle is added to it.