Can confirm same behavior on mine.

Phone will cycle a few time, attempting and failing to go into USB_HVDCP (It doesn't manage to negociate 9V).

Eventually, it settles on charging at 5V only.

Every once in a bluemoon, I discover the phone actually successfully handshaked a 9V charging from the QuickCharge charger.

This is only for QuickCharge (USB-A connectors on chargers that can supply 9V/12V in addition to the classic 5V).
It doesn't happen on PowerDelivery (USB-C connectors on chargers), the phone keeps 5V and just asks for a higher current (2.5A) which is successful nearly all the time.